'I am vehemently opposed to having loaded weapons on an aircraft,' the pilot of 25 years' experience told colleagues afterwards. 'So I asked the guy to come to the front of the aircraft, so I could inspect the gun and make sure it wasn't loaded.

'He showed me his gun. Then when I asked him to produce the ammunition, he opened the breach and there were the bullets inside. It was a full metal jacket round. It could probably fire a hole straight through the person it was aimed at, as well as any structure that came in its way.'

With a flight attendant acting as interpreter, the pilot asked the bodyguard to disarm his weapon. The bodyguard politely complied and the plane took off on schedule without passengers being aware of the fleeting drama.

The incident sheds light on arrangements on Dragonair planes operating on the mainland that is causing considerable anxiety among the pilots and which might also surprise passengers flying between the mainland's ultramodern domestic airports.

When Dragonair signed a wet-lease contract to provide six Airbus A330s and A320s to Air China - operating routes between Beijing, Shanghai, Shenzhen and Guangzhou - the Hong Kong airline was asked to apply mainland security measures on those flights.

That meant allowing an Air China in-flight security officer to board every flight - armed with a 7cm-8cm dagger, handcuffs, rope, torch, screwdriver and pliers, and authorised to act independently to subdue a hijacker. More significantly, it also meant allowing VIP passengers to be escorted by a bodyguard armed with an unloaded QSZ-92 pistol and 10 rounds of ammunition.

Those bodyguards might be compared to the air marshals deployed on American planes in the US since the 2001 terrorist attacks, apart from two crucial differences. The VIP bodyguards, unlike air marshals, do not appear to have weapons modified to ensure they cannot damage the aircraft's body and, unlike air marshals, they're there to protect one person and not the passengers in general.

The obstacle to allowing armed bodyguards and security guards on board was that, as Hong Kong-registered aircraft, the Dragonair planes are subject to Hong Kong Civil Aviation Department (CAD) rules on security - and those rules allow no guns inside the passenger cabin. The rules, debated intensely by the government, airlines and pilots' representatives in the wake of September 11 - clearly state that no offensive weapons should be carried on board Hong Kong-registered planes.

The no-weapons rule has the support of the Hong Kong Airline Pilots' Association, which has taken up the issue on behalf of the Dragonair pilots. 'The place for security is on the ground, not on the plane,' said president David Newbery, a Cathay Airbus captain. 'An aeroplane is not the place to have a gun fight.

'I have flown planes carrying George Bush Snr and the president of Sri Lanka. On each occasion they have been accompanied by armed guards - but the guards had to put their guns into the hold for the duration of the flight.'

Dragonair management got around the rule by applying to the CAD for a dispensation so that armed security officers and bodyguards would be allowed on board the wet-leased flights.

That exemption was granted with no prior consultation with pilots who, according to pilots' association, only learned of the arrangement when a confidential memo was sent out by Dragonair management in October.

That memo, seen by the South China Morning Post, details how pilots are expected to carry in-flight security officers in civilian dress, answerable to the captain but carrying their dagger and handcuffs security kit on all wet-lease flights.

Senior government ministers or foreign heads of state, meanwhile, are accompanied by armed VIP bodyguards carrying pistols and ammunition and exempt from anyone's authority. The bodyguards are 'not directly responsible to the aircraft commander and may act independently to protect their charge', the memo said. The VIP bodyguards - who can fly armed even when they're not accompanying a VIP but on their way to an assignment, according to the memo - appear to take seriously their freedom to act independently, with some pilots describing them as 'intimidating and arrogant'.

One Australian Dragonair captain reported having an uncomfortable encounter with two government bodyguards on a flight from Guangzhou to Beijing on September 21 last year, before the new arrangement was officially approved, when he asked them to submit to body searches before boarding the aircraft.

Take-off was delayed 30 minutes when one of them initially refused to be searched in a bad-tempered confrontation and the bodyguards later demanded to speak to the captain mid-flight to ask for an explanation for the searches, a request that was refused.

When the plane touched down, the bodyguards would not leave the plane, demanding to know which hotel the pilot would be staying at in Beijing, the captain recalled in a report afterwards.

The captain told the pilots' association he considered calling airport security to 'forcibly remove them' but reported: 'It was later ascertained that as government official bodyguards, their power was superior to any security at the airport and [they] were not scared of any retribution. The senior purser was finally able to convince them that I would not disembark until they were back in the terminal. She gave them my name and hers and the contact numbers for the station manager of KA [Dragonair] in PEK [Beijing].'

The pilot was so concerned that the bodyguards might be 'trying to ascertain our whereabouts through government channels' that arrangements were made for him and the senior purser to switch hotels on security grounds.

The pilots' association has written twice to CAD director-general Norman Lo Shung-man expressing 'serious concern' about the behaviour of the armed bodyguards - carried on five occasions between November and February, according to CAD records - and calling for talks to establish a clear protocol.

One Dragonair pilot who has carried an armed bodyguard remarked: 'I don't know of anywhere else in the world, except maybe in South America, where this kind of arrangement would be permitted. It doesn't happen anywhere in the developed world that I know of.'

In one letter to Mr Lo, the pilots' association said: 'Hong Kong-licensed flight crew, operating a Hong Kong-registered aircraft, should expect to have a level of security and safety guaranteed by Hong Kong law, not imposed by a foreign airline.'

The dispensation allowing the armed bodyguards on board seemed to have been given 'solely as a result of commercial and, possibly, governmental pressure', it said. 'If certain individuals require armed bodyguards in flight then they should travel in a chartered aircraft or with an airline where comprehensive protocols have been established.'

Pilots are particularly concerned at the legal implications of any gun fight on board a plane. As captain, they fear they may be held legally responsible but say requests to be given a copy of the CAD dispensation allowing armed bodyguards on board has been refused.

At a meeting between Dragonair Pilots Association president John Edwards and a Dragonair management official, Mr Edwards was shown a copy of the dispensation but told colleagues afterwards: 'I was only shown it briefly, they wouldn't let me have a copy and they wouldn't let it out of their sight.'

CAD director-general Mr Lo declined requests for an interview but in an e-mailed statement, a CAD spokesman said the dispensation had been granted 'to meet the requirements of the mainland's authorities'.

'Current regulations ... require that all flights within mainland China should be deployed with in-flight security officers, and that for flights carrying senior government officials, armed bodyguards should also be deployed.'

The CAD said there were communications and discussions within Dragonair in regard to the implementation procedures and arrangements for in-flight security officers and armed bodyguards. A spokesman said Dragonair notified its crews of operating procedures and arrangements for the carriage of in-flight security officers and armed bodyguards on its aircraft wet-leased to Air China for mainland operations.

Dragonair issued a statement saying that its wet-lease services on mainland routes for Air China operated in accordance with the regulations of the relevant central government authorities.

'As a Hong Kong-registered airline, Dragonair required approval from the Hong Kong Civil Aviation Department to meet these regulations and approval was granted,' the statement said.

'Our air crew and their representatives have been fully informed of the situation. Given that this is a matter related to security, we are unable to provide further details on this arrangement.'

A request to see the dispensation issued by the CAD was refused, and both the CAD and Dragonair declined to answer questions about incidents involving VIP bodyguards and the weapons they carry, citing security reasons.

However, a letter sent to the pilots' association on behalf of Mr Lo in November said: 'Since the programme and the arrangements for deploying bodyguards to protect government VIPs have been in operation on the mainland for many years, we are confident that all security personnel engaged in Air China flights on Dragonair's wet-leased aircraft are specially selected and trained.'

The biggest worry among Dragonair's pilots is that the guns would be used on board either by a bodyguard or by someone who had snatched the weapon from a bodyguard.

Only once has a pilot insisted on checking a bodyguard's weapon - and on that occasion, last December 6, it turned out to be fully loaded.

Pilots' association president Mr Newbery said talks with the CAD were urgently needed to ease pilots' concerns, but his requests had so far been rebuffed. 'We have a very good relationship with the CAD and a very good working relationship. On this issue, however, they have shut us out and we find that quite distressing.'

Pilots were willing to consider accepting armed bodyguards if a 'coherent case' was made, he stressed. 'If the protocol for the carriage of armed personnel is arranged correctly and it is established that the captain is in overall charge of the plane, we may be able to accept the arrangement,' he said. 'But we need to sit down and talk.'