London mayor Boris Johnson has admitted that private funding sources may not be able to cover the £56.9m cost of the proposed new River Thames Cable Car service.

In April, Johnson revealed that Mace is to lead a consortium of contractors to build the new Wilkinson Eyre-designed link between Greenwich and the Royal Docks.

However, the mayor said at the London Assembly's Question Time on 15 June that there is no "guarantee" the private sector would be able to cover the cost of the scheme.

John Biggs, the assembly member for City and East, said: "It is an attractive scheme and will hopefully make an impact but it is mainly for tourists and is not a serious transport project."