Gareth Bacon, Conservative Assembly member and chairman of the Budget and Performance Committee said: "The mayor has decided to increase council tax next year to help fund the Met Police. He will have to explain to the Assembly – and to Londoners – why this is the best way of dealing with the cut in government funding announced last week."
The mayor proposes increasing the police precept element of council tax bills by 1.99 per cent, adding £4.02 to the average Band D property. Government funding for the Met is due to fall by £17.4m compared to 2015-16.
He added that there were also concerns over TfL’s fares income, which "could be less than expected" unless it solves the problems of the capital's congested roads.
The committee's other worries included TfL's plans to significantly up its borrowing to finance its business plan, with a forecast of debt reaching over £12bn by 2020-2021.
Bacon said TfL's new business plan "lacks any meaningful detail about how it will actually deliver these promises".
The committee wants details for how TfL plans to deliver efficiency savings of £800m per year by 2020-21 and the timescales involved.
"The previous mayor refused to do it, but in reorganising a flabby TfL and finding major efficiency savings within the organisation, we’re securing this record investment without burdening Londoners with further hikes in TfL fares," he said when the plan was unveiled earlier this month.