A new bridge had been planned from the tip of the old runway to Kwun Tong but a recent study by the department found this might not be feasible in the short term because the construction could infringe the Protection of the Harbour Ordinance.

'To allow vessels to pass under the bridge, it would have to be very high, which is not very user-friendly,' a spokesman for the Development Bureau said.

As an alternative, the department is studying the feasibility of extending the monorail to neighbouring areas, including Kowloon Bay and Kwun Tong, across an existing bridge.

The preferred route would be from the MTR stations in Kwun Tong and Kowloon Bay to Kai Tak station on the Sha Tin-Central Link. The rail system is expected to be completed in 2021, subject to the detailed design.

'The extended rail link looks more user-friendly and it serves the same purpose, strengthening the connection of old and new districts,' the bureau's spokesman said.

But the spokesman said the study was still at a preliminary stage and a lot of problems had to be solved to implement the plan.

He said the government had to ensure streets in old areas were wide enough for the monorail.

Construction work on the monorail could also be complicated by the busy road traffic and the public utilities carried underground.

The Development Bureau will seek funding of HK$1.18 billion from the Legislative Council for the infrastructure and detailed design of Kai Tak, including a study of the monorail. The infrastructure is expected to be completed in three phases: public housing, cruise terminal and waterfront promenade in 2013; residential development, underground street to Kowloon City and San Po Kong, heliport and Kai Tak station in 2016; and monorail, stadium complex, remaining residential and commercial developments, and the last stage of the district cooling system in 2021.

The first phase is expected to commence in July this year.