Delays in improvements for the London bus network could disrupt the start of congestion charges in the capital, Mayor Ken Livingstone warned yesterday.

Giving his backing to the scheme, in which drivers would be charged £5 to drive into Central London, he said a review of the start date, currently planned for Spring 2003, would go ahead in the Autumn if buses were not yet improved sufficiently to cope with an estimated 20,000 extra passengers.

However, the Transport for London traffic management section has warned that the Greater London Authority have over-estimated the impact of the charge on public transport, claiming that most drivers would stay in their cars.

The London Transport Users Committee agreed, but expressed sympathy at the "loophole" created by Livingstone.