A "staggering" £11.6 million has been spent on replacement buses because of engineering work on one of London Underground's lines, it was revealed today.
The Liberal Democrats said weekend closures on the Jubilee Line, which it said has caused years of disruption, has led to a "huge" bill.
The party's London Assembly leader Caroline Pidgeon said answers to questions posed to Mayor Boris Johnson showed that Transport for London (TfL) paid out £5.7 million for replacement buses in the year to March, taking the total since 2006 to a "staggering" £11.6 million.
Ms Pidgeon said: "The delayed upgrades to the Jubilee Line has been bad enough for passengers and businesses, who have had to put up with terrible disruption and closures for far too long. It is now rubbing salt into the wound to discover that farepayers are picking up another huge bill.
"Such huge expenditure on replacement buses is just one further reason why a new approach to Tube upgrades is necessary. Completing upgrade work in a much shorter space of time - with block closures if necessary - would be good for the Tube and passengers. TfL and the Mayor need to have an urgent rethink."