Construction of Thames cable car will soon to be underway, say Transport for London (TfL), as they start the search for private investment.

But London Mayor Boris Johnson has admitted that the taxpayer may be lumbered with the costs.

To questions from East London Assembley member John Biggs the said that he could not “guarantee” that the private sector would be able to cover the �56.9m cost of setting up the Cable Car scheme.

Mr Biggs said: “It is an attractive scheme and will hope make an impact but it is mainly for tourists and is not a serious transport project.”

He said a new road bridge or tunnel was urgently needed.

This week TfL have opened an Invitation to Tender for a commercial partner to sponsor the overhead link between Newham and Greenwich.

The development, TfL trumpets, represents “a unique and exciting opportunity” for the private sector to be associated with what will be one of London’s internationally recognisable landmarks with unprecedented exposure on one of the busiest transport networksin the world.

The target is to have the cable car operation connecting the Greenwich Peninsula and the Royal Victoria Dock, running by next year’s Olympic Games.

As the UK’s first urban cable car it will be a spectacular architectural addition to London’s skyline.

Chris MacLeod, Director of TfL Group Marketing, said: “Sponsorship of the cable car offers a unique and exciting opportunity for a leading company to be entwined within the fabric of London.”

A commercial partner is promised high visibility opportunities for their brand at stations and gondolas and on the iconic Tube map.