Barnet and Camden Assembly Member Brian Coleman has been labelled a "hypocrite" after running up a further £4,157 in cab bills over the last nine months.
The figures released by the Greater London Authority (GLA) last week take the deputy chairman's total taxi expenses since April 2004 to £17,204.59 - nearly six times that claimed by London Mayor Ken Livingstone, whose bill for the same period was £2,887.01.
The figures cover both taxis that are ordered via the GLA, for which no money changes hands, and taxis that are paid for directly by the Assembly Member and then claimed back.
The latest expenditure, covering the period between April 1 and December 31, 2007, accounts for nearly half the entire cab account of the 24 Assembly Members and Mr Livingstone combined, with the average bill totalling around £370.
Mr Livingstone, however, did tally up an "other expenses" bill of £4,770.09.
Mr Coleman, like all Assembly Members, is entitled to a free travel card for zones one to six so that he can make the majority of his journeys on public transport.
His total bill since April 2004 is more than 48 times the cost of providing annual free bus travel for a child under 16 - a concession that nine Conservative Assembly Members, including Mr Coleman, voted to abolish in February 2007.
Councillor Kathy McGuirk, Labour spokeswoman for the environment, said: "Brian Coleman wants to scrap free bus travel for school children, while expecting the council tax payer to cough up thousands of pounds for his cabs. It's Tory hypocrisy of the worst kind."
Mr Coleman said that the figure was so high because, as deputy chairman, he attends "considerably more events than any other Assembly Member" in fulfilling his role.
He added: "The figure represents costs of the taxi that is ordered for me to attend official functions. It is not for taxis that I order myself."
But Mr Livingstone said this explanation was not good enough.
"Brian Coleman must explain to Londoners how he can possibly justify spending more on taxis in four weeks than the average Assembly member does in nine months.
"While Brian Coleman was being chauffeured around the capital, he voted for cuts for the London Fire Brigade budget and spoke out against the introduction of 21 strong safer transport police teams in London."