HONG KONG • China has finally announced the opening ceremony for the world's longest sea bridge, which will connect Hong Kong, Macau and the mainland, but critics hit back yesterday over the secrecy surrounding the project.

Construction started in 2009 on the 55km crossing, which includes a snaking road bridge and underwater tunnel, linking Hong Kong's Lantau Island to the southern mainland Chinese city of Zhuhai and the gambling enclave of Macau, across the waters of the Pearl River estuary.

It has been dogged by delays, budget overruns, graft prosecutions and the deaths of construction workers.

While supporters promote it as an engineering marvel, others see the multibillion-dollar project as a costly white elephant designed to further integrate Hong Kong into the mainland at a time when Beijing is tightening its grip on the semi-autonomous city.

Local media received invitations from Beijing's liaison office in Hong Kong on Wednesday to an "opening ceremony" in Zhuhai next Tuesday, with no further details given.

Chinese President Xi Jinping is reported to be attending the event, but there has been no official confirmation on whether the bridge will go into operation that day.

Hong Kong's Transport Department had no immediate answer yesterday when asked whether the bridge would be fully commissioned next Tuesday.

Bus companies that are supposed to be operating on the bridge complained they were in the dark. "At such short notice and without any details, how can we make the necessary logistic arrangements?" Mr Eddie Choi, a spokesman for coach operator One Bus Hong Kong Macau, told the South China Morning Post.

An official from the mainland-based bridge authority told Agence France-Presse the bridge would be "considered open" from next Tuesday and confirmed that there would be access that day to registered cars and buses, but did not elaborate.

The China Daily newspaper cited a source familiar with the matter as saying the bridge would be open to traffic later in the day, after the opening ceremony.

Pro-democracy lawmaker Kwok Ka Ki, who sits on the Hong Kong government's transport panel, said he learnt of the launch ceremony from media reports only on Wednesday and had not received an invitation to the opening.

Members of the transport panel have been invited to a bridge inspection tomorrow, according to panel member Tanya Chan.

Mr Kwok accused officials of secrecy. "The bridge needs to be open and used by the public as soon as possible, but whether it is safe and arrangements are properly in place... we do not know," he told AFP.

AGENCE FRANCE-PRESSE