Lawmakers who will scrutinise Hong Kong's 6.75 billion yuan (HK$7.65 billion) contribution to the project said a fair mechanism must be set up to ensure each government had an equal say regardless of who led the group.

Hong Kong's Transport and Housing Bureau was named convenor when the committee was set up in 2003 to take care of preparatory work. But with construction due to start next month, the committee's name and function will be changed.

It will be part of a three-tier structure that determines important issues, including charges for using the bridge and vehicle admissions, which will affect its use and income.

The committee will be sandwiched between a high-level body comprising Beijing representatives, including the National Development and Reform Commission and the Ministry of Communications, and a new bureau under it to oversee the bridge's daily operation.

But as most of the 29.6 kilometre bridge falls within the mainland's jurisdiction, and as it contributed the largest share of the budget, Guangdong was chosen to lead the new committee, sources familiar with the project said.

In fact, Guangdong only has to pay two billion yuan up front for its share of the 37.73 billion yuan main bridge - less than one third of Hong Kong's share. But because Beijing committed five billion yuan to Guangdong's share last August to speed up the project, the share to be paid by the pair increased from 35.1 per cent to 44.5 per cent. Hong Kong's share is 42.9 per cent.

Contributions from the governments made up 42 per cent of the total cost while a private consortium led by the Bank of China will finance the remainder, or 22 billion yuan, at an interest rate 10 per cent below its benchmark lending rate - the lowest allowed by the state authorities.

A local government official said it did not matter who led the committee because the consent of all governments must be obtained before a decision could be made. In cases where differences cannot be resolved, Beijing - which will have delegates but no members on the committee - will intervene.

A mainland source said the new convenor would work as a mediator for the three governments rather than just a representative of its province.

But Zheng Tianxiang, a delta transport specialist at Sun Yat-sen University in Guangzhou, said consensus would be difficult to reach on matters where interests were divided - such as admission of vehicles - and it would be better if the three governments took turns as convenor. 'Guangdong has always wanted more mainland vehicles allowed into Hong Kong, but Hong Kong has limited road handling capacity and also environmental concerns,' he said.

Democratic Party lawmaker Lee Wing-tat said there should be a voting system.

Secretary for Transport and Housing Eva Cheng said in August that private cars might pay less than HK$100 to use the bridge and trucks about HK$200. But that assumes that at least 9,200 vehicles a day used the bridge upon its opening in 2016, and its success will depend largely on an ad hoc cross-border vehicle permit system still being negotiated.

A chief executive will be recruited globally to head the bureau that oversees daily operations. But as the annual salary proposed in an early feasibility report was just 600,000 yuan, the position may be more attractive to mainland candidates than experienced Hong Kong managers.