The announcement came after the first meeting of a joint taskforce of Hong Kong and Shenzhen authorities yesterday over the feasibility of the concept.

Ms Cheng said two expert groups comprising government officials and members of public utilities would be commissioned to research the project. Their investigations would be expected to finish by the end of the year but at this stage no cost estimates could be made or decisions about any stops on the route.

The associate director of the Aviation Policy and Research Centre at Chinese University, Law Cheung-kwok, said stops on the line somewhere within Hong Kong would increase the line's economic viability, although this had security implications.

'There were only 500,000 passengers for the Skyrail service between the two airports in 2006,' Dr Law said. 'It boils down to a daily average ridership of just 1,400 passengers. That is not nearly sufficient to support the operation of a railway.'

However, creating stops would also slow the service down.

As the rail link's prime purpose was to boost passenger throughput between the airports by quickly moving transit passengers not cleared by Hong Kong or mainland immigration, there would have to be a mechanism disallowing uncleared passengers from leaving the train, he said.

The joint taskforce's next meeting will be in Shenzhen.