Hong Kong would cover 50.2 per cent of the shortfall, Guangdong 35.1 per cent and Macau 14.7 per cent.

Secretary for Transport and Housing Eva Cheng said the ratio followed the cost-to-benefits principle.

'The three sides agreed that the three governments would be responsible for the construction and operation of the boundary-crossing facilities and the connecting roads to the bridge within their own territory. We agreed to share the amount of the subsidy under the cost-to-benefit ratio,' she said.

Zhang Xiaoqiang, deputy chairman of the National Development and Reform Commission, said earlier that Hong Kong would enjoy 64 per cent of the economic benefits brought by the bridge.

Ms Cheng refused to say how much the bridge would cost and the amount of subsidies provided by the government, fearing it would affect the outcome of the bidding process for the project.

But the head of the Advance Work Co-ordination Group's project office, Zhu Yongling, said earlier the main body of the bridge was expected to cost between HK$30 billion and HK$40 billion, plus another HK$20 billion on infrastructure such as connecting roads and border checkpoints in the three cities.

Talks became bogged down last year by disputes over issues such as the location of checkpoints and the sharing of construction costs.

Successful bidders will form a consortium to construct and operate the bridge for 50 years.

Sir Gordon Wu Ying-sheung, chairman of Hopewell Holdings, who first proposed the project in the early 1980s, has been a passionate advocate of it ever since. Yesterday his son, Thomas Jefferson Wu, co-managing director of Hopewell, said he was happy the longdebated idea would finally become a reality. He said Hopewell, which had about HK$9 billion in cash on hand, would consider lodging a bid.

Other interested companies include the Sun Hung Kai group, New World group and China Communications Construction Company, which is carrying out a feasibility study on the bridge for the co-ordination group.

Kwan Chuk-fai, general manager of NWS Holdings, which has invested in many mainland infrastructure projects including roads and railways, said the group found the project attractive because use of the bridge was guaranteed by strengthening logistics and tourism between the three cities.

The chairman of the Container Transportation Employees General Union, Tse Long, expected that up to a million container trucks a year would use the bridge, as it would save at least two hours per trip from western parts of the pan delta region compared with shipping cargo.

'If the toll was set at around HK$100 to HK$150, it would be very popular among container trucks.'

The main body of the bridge, measuring 29.6km, is expected to run from San Shek Wan in Lantau to Gongbei in Zhuhai and A Perola in Macau. Travelling time between Hong Kong and Macau and Zhuhai will be shortened from an hour to between 15 and 20 minutes.