CONCERNS have been raised by government officials at the lax way China informed Hong Kong of a potential danger to planes flying over Guangdong. Airline pilots have been warned to avoid an exclusion zone near the town of Haifeng, about 100 kilometres east of Hong Kong, while the area is used for a military exercise. Firing with live ammunition is to take place from 8 am to noon and from 3 pm to 7 pm each day until the exercise is completed next Wednesday. The Civil Aviation Department (CAD) was first told of the exercise and asked to direct flights away from the area in a message to the air traffic control centre duty officer on Sunday. Only later was the normal procedure of issuing an official Notice To Airmen (NOTAM) followed by China, and the CAD director informed. Other government departments, such as the Security Branch and the Government Flying Service (GFS), have not been told of the exercise. But while this is accepted, one official complained that, at the very least, the CAD should have received the official notice as the first communication from China rather than a message passed to a weekend duty officer. ''It is difficult to criticise the Chinese, but there is some annoyance that they went about this the wrong way,'' one government official said. ''The NOTAM is the official way to alert people not to fly over a certain area and that is how Hong Kong should have been informed. ''It is a shame that that did not come first.'' The NOTAM, which is forwarded to all pilots, said the military exercise started on Monday and had an operating altitude of 8,800 metres. It is not clear what sort of weapons are being used during the exercise or what its aim is. The mainstay of the People's Liberation Army (PLA) air defence system remains the SA-2 Guideline medium-range surface-to-air missile, an old but reliable weapon, one of which was used by the Soviet Union to shoot down the American U-2 spy plane of Gary Powers in 1960, defence sources said. More sophisticated missiles, similar to the Patriot system used by the United States against Iraqi attacks in the Gulf War, have been ordered by the PLA, although it is understood they have not yet been delivered. Sources said that given the exclusion zone's relatively small diameter of just 13 nautical miles, the PLA could just be using small anti-aircraft artillery as seen in the Bosnian conflict as well as their AK-47 rifles. Flights to Hong Kong from Tokyo or Taipei would usually pass south of the exercise zone, although pilots tend to move northwards to avoid bad weather and that action is likely to be curtailed until the firing practice is over. Hong Kong air traffic controllers have been asked to alert their counterparts in the neighbouring Guangzhou flight information region if any planes are heading towards the exercise zone. But sources said there was no guarantee the exercise would be halted. Spokesmen for various government departments, including the Security Branch and the GFS, yesterday confirmed they had not been notified of the PLA exercise. Helicopter patrols by the GFS around the border have not been affected, nor have any operations planned by the British Garrison. Cathay Pacific Airways and Dragonair said they did not expect their flights to be affected.