Mayor of London Ken Livingstone should focus on long-overdue transport projects like the Thameslink 2000 upgrade rather than extending the congestion charging zone westwards, according to a business lobbying group.

Mr Livingstone announced last week that he is to double the size of the congestion charge zone, first introduced last year, by extending it over much of Kensington and Chelsea. But the business campaigning organisation London First, which strongly backed the introduction of the congestion charging zone last year, said it was not convinced the extension was worth the money and that the Mayor, and Transport for London (TfL), ought to have higher priorities.

"We would prefer to see the Thames Gateway bridge, Thameslink 2000, the East London line and some of the vital road upgrading schemes around London accelerated," said campaigns director Julia Lalla-Maharajh.

The Thameslink upgrade, which would allow more trains to stop at Cricklewood and Hendon, was supposed to have been completed four years ago but is still bogged down in the planning stage.

TfL would not comment.