David Cameron and Nick Clegg have been accused of breaking their promise to curb the numbers of ministerial special advisers after official figures showed their pay bill has risen to more than £8 million.
A list published by the Cabinet Office showed there are 107 so-called "Spads" working in Whitehall - including four appointees to the Council of Economic Advisers - employed at an annual cost of £8.4 million, up from £7.2 million the previous year.
They include a total of 26 working for Mr Cameron in Downing Street and 20 working for Mr Clegg.
Labour said the figures showed that the overall numbers of special advisers had risen inexorably under the coalition from 71 in 2010 to 74 in 2011, 83 in 2012 and 98 last year.
Answering business questions in the Commons, Leader of the House William Hague said the rising numbers reflected the "nature of coalition" and that their average pay was actually lower than it had been under the previous Labour government.
The Prime Minister's official spokesman said that special advisers' pay was now on average £5,000 a year less than it had been under the last government.
But shadow leader of the House Angela Eagle accused the Conservatives and Liberal Democrats of breaking a commitment in the coalition agreement to limit the number of the special advisers - many of them direct political appointments by ministers.
"David Cameron promised to get the cost of politics down but under him the number of special advisers spirals ever upwards - the public are now picking up a bill of over £8 million to pay for his appointees," she said.
"This also shows how you can't trust a word Nick Clegg says. The Lib Dems used to say that special advisers shouldn't be paid for by the public but as soon as he got his feet under the Cabinet table, he broke his word."
The rising cost of special advisers was also criticised by Ukip. The party's economic spokesman Patrick O'Flynn said: "What we really need are more real doctors and less Government spin-doctors."
The Cabinet Office list showed that six advisers are paid £100,000 or more, with the list topped by Mr Cameron's chief of staff Ed Llewellyn and his director of communications Craig Oliver, who each received £140,000.
Christopher Lockwood, deputy head of the No 10 policy unit, received £134,000; the Prime Minister's press secretary Graeme Wilson got £110,000; and Kate Fall, Mr Cameron's deputy chief of staff, received £100,000.
Mr Clegg's director of communications, Steve Lotinga, received £105,000.
A Cabinet Office spokesman said: "As part of this Government's long-term economic plan, we are making efficiencies from the Civil Service, which is now 21% smaller than it was at the time of the 2010 general election.
"Workforce reductions and pension reforms saved £4.7 billion last year, compared to a 2009/10 baseline. Special advisers perform an important function and their average salary cost is 8% lower now than under the previous government."