Something that worried BAR was the Airport Authority's monopoly in providing airport services. Mr Chow pointed to Chek Lap Kok's high cost base for airlines and also for retailers as a cause for concern. 'Rents at Chek Lap Kok are, to a degree, a legacy of the Kai Tak era,' he said. 'Certainly, there is an adjustment mechanism, but the base was set very high.'

Will a privatised airport be completely focused on maximising profits for shareholders, at the expense of the airport's responsibility as a major economic driver for Hong Kong?

Another concern was whether a privatised airport would be too focused on maximising profit for shareholders at the expense of customers. 'It is important to remember that the airport should not be just a private company looking to maximise profits. It serves a public good and should be there to benefit the whole community. The government can't escape that ultimate responsibility,' he said.

Privatisation must conform to standards laid down by the International Civil Aviation Organisation (ICAO), an arm of the United Nations that governs international air transport, that the Hong Kong government had ratified, Mr Chow said. 'The principle is that airports ultimately perform a public service. Profits must be rolled back to users.'

Airline representatives say that it costs them $25.90 a month to rent one square foot of office space at the airport. By comparison, the Mass Transit Railway Corp is said to be offering space at Two International Finance Centre in Central for $12 to $15 per square foot. 'Retailers can choose not to set up shop at the airport, but airlines have no choice. We're a captive market,' one airline executive said.

As such, industry support for the privatisation of Chek Lap Kok may hinge on the government's proposal to move the Airport Authority away from its present 'single-till' accounting system towards a 'two-till' system. While the single-till system combines all revenues and costs into one account, a two-till system separates aviation and commercial activities into two separate accounts. The rationale for changing the system would be to separate the two activities and better assess profitability. It would then set airline charges and commercial leases separately rather than combining the two.

Consultants say the biggest weakness to the two-till system is the subjective issue of how costs are allocated between aviation and commercial activities. Increasing retail operations in an airport terminal often involves higher costs for security and safety. 'Will these things be fairly split up? And can a formula be agreed upon that will ensure that the costs are always adjusted on a real-time basis for day-to-day situation changes?' said a Singapore-based aviation consultant. 'This is a real issue that will determine how fair an accounting system the two-till system is for both airlines and retailers. Otherwise the airlines will just see this as an excuse for the airport managers to raise charges in the future.'

Tony Concil, a regional spokesman for the International Air Transport Association (IATA), an airline industry organisation, questioned whether the two activities could be separated. 'The basic premise of setting up a business at an airport is that passengers and people connected with air travel will make purchases. People do not go to the airport for the express purpose of shopping. Without the airlines bringing passengers in, the shopping mall would be empty. Remember, the easier it is for airlines to bring more passengers to the airport, the easier it is for the concessionaires to make sales.'

Not everyone agreed that privatisation would mean higher charges for airlines at Chek Lap Kok. Airports Council international secretary-general Alexander Strahl said that 'privatisation is a global trend' that would accelerate as airport operations became increasingly complicated by non-aviation commercial activities. 'People think that airport privatisation means there will be higher [user and landing] charges as a result. But it is not necessarily so.'

The head of the Geneva-based organisation, which represents more than 1,700 airports around the world, including Chek Lap Kok, refused to comment specifically about the Airport Authority's case for privatisation, as 'circumstances differ from airport to airport and from country to country'. But he said: 'Privatisation is not an end to itself, it's a form of ownership to deal with growing traffic and capital needs for expansion. Governments nowadays are cash-strapped. Even if they had the money, governments would rather be putting it into things like education.'

Mr Strahl said airport managers were also becoming more entrepreneurial. Although in the past airports were basic facilities for air travel, they had since become more experience-oriented with retail and entertainment facilities to draw travellers. 'Commercial activities are a much bigger part of airport revenues now. And they are having to become more and more entrepreneurial,' he said.

Privatisation would also force airports to streamline operations. 'They will have to be more efficient. Airports not efficiently run will not be able to attract investors,' Mr Strahl said.

But according to one senior executive of a prominent local infrastructure investment company, if airport commercial operations are becoming more entrepreneurial in nature, 'why not just list the commercial operations of the airport and leave the aviation side the way it is?'

'There's not much management skill needed to operate the aviation side of the airport,' he said. 'Airlines are a captive market, so all the managers need to do is make sure that their costs remain low and make sure that the airlines are happy enough to keep flying here. This type of classic infrastructure business is not suitable for a stock-market listing because there's little scope for growth based on management skill; it's more suitable for bonds and securitising cash flows to investors interested in a steady return for their money.

'But a case can be made that a lot of skill is needed to make the commercial operations run well, similar to the talent involved in running a large shopping mall. So separate it out, and list that instead. It goes hand-in-hand with the government's two-till accounting proposal, too.'

Ultimately, getting the airlines on-side to any airport privatisation proposal may be tricky. Geoff Dixon, chief executive of Qantas, said: 'Airport privatisations just turn a government monopoly into a private monopoly. I don't think it's a good idea and it is fraught with great dangers.'

Looking at recent Australian examples, Mr Dixon said the strategy for governments 'was to try to get its money back, to the maximum extent possible'. Meanwhile, investors 'are only concerned with trying to maximise their own returns'. Neither demand serves the public or airlines, supposedly the key stakeholders in every airport.

'I haven't seen more efficient airports emerging as a result of privatisation,' Mr Dixon said.