Boris Johnson today accused government ministers of causing the recession that it was now "rejoicing" in.

The Conservative mayor of London singled out Ed Balls for particular criticism as he rejected the children's secretary's suggestion that the recession was the worst in 100 years.

Johnson blamed the government for exacerbating the recession as he presented his revised budget to the London assembly.

"This budget is substantially unchanged and is what I believe is demanded by the times," said the mayor. "London faces a recession exacerbated by government wastefulness and in particular by the level of indebtedness.

"We now have the fresh challenge of government ministers asserting that this is going to be the worst recession in 100 years. I do not believe that to be true and I believe that Ed Balls is aptly named."

The children's secretary, who for many years was one of Gordon Brown's closest advisers, has warned that the crisis may be "more extreme" than the one in the 1930s.

Johnson made further criticisms of Balls after he became embroiled in an ill-tempered discussion with members of the London assembly's Labour group on the merits of his £12.2bn budget.

The Labour group taunted Johnson by claiming that his predecessor, Ken Livingstone, had managed to make more savings than those the Tory mayor had achieved.

They also criticised moves such as dropping the next phase of the low-emission zone, which would have targeted the most polluting vans driving around London, and bringing in above-inflation transport fare rises.

Johnson retorted: "I really think that the Labour group have distinguished themselves by their apathy, their indolence, their hopelessness and their general inability to produce anything to distinguish themselves from the absolute gloom and despair offered by Labour government ministers like Ed Balls, who now seem to be rejoicing and wallowing in the very recession that Labour caused."

Johnson said he was proud of his budget, which would see a freeze on the Greater London authority's share of council tax for the first time in eight years and, he said, keep down Londoners' household bills.

Johnson told the assembly: "We must do everything we can to ease the burden on Londoners, make our city safer, promote green technology that could offer the hope of long-term recovery for the economy, and to step up the investments in the infrastructure that will generate jobs and growth in the short term and that will make the city more attractive, greener, easier to live in and move around in, and more competitive as we come out of this recession."

Johnson was put on the back foot by the Liberal Democrats during the question-and-answer session over the bonus culture at Transport for London (TfL), which he chairs.

Figures obtained by the Lib Dems show that 677 TfL employees were paid a performance bonus award worth more than £2.9m in 2007-08.

The London Evening Standard reported yesterday that 123 TfL managers earned more than £100,000 in 2007-08, according to figures obtained under a freedom of information request.

By contrast, the Treasury, responsible for the entire British economy, had just 15 six-figure earners.

Johnson said that bonuses were necessary to have the best staff in place to deliver major infrastructure schemes such as the Crossrail project in order to avoid racking up extra costs later.

But he said staffing numbers and remuneration packages would be part of a review to achieve efficiencies worth £2.4bn over the next 10 years. "I am conscious of people's feelings. I understand their concerns and, of course, we will be reviewing salaries as well as staffing numbers," he said.

Johnson used his weekly Telegraph column yesterday to denounce the "outrageous" bonuses being paid to bankers whose institutions are in receipt of billions of pounds of taxpayers' money.

"I hope my friends in the City will not mind if I say that it is unbelievable – totally and utterly unbelievable – that banks in receipt of billions of pounds of taxpayers' money should be using some of that money to 'reward' their star performers," he wrote.

"If these people have an ounce of sense or decency they should either forgo the dosh or give it to charity.

Caroline Pidgeon, the Lib Dems' transport spokeswoman in the assembly, said later: "It is extremely disappointing that the mayor is not willing to give a firm commitment to curtail the bonus culture within TfL. Only this week the mayor has made forceful comments about the bonus payments made to bankers. The mayor should spend less time writing newspaper columns about issues he cannot control and instead turn his attention to addressing something that he is directly responsible for."

The London assembly approved the mayor's budget today, which outlines plans for £9.3m of efficiency savings for the Greater London authority, £92.3m for the Metropolitan police, £8.2m for the fire authority and £7.6m for the London Development Agency, as well as a freeze on the GLA levy (precept) included in Londoners' final council tax bill.

The budget can only be blocked by a two-thirds majority on the 25-strong assembly, which includes 11 Conservative members.

A budget amending motion urging the mayor to develop "a more robust long-term spending strategy to ensure a prosperous, healthy and sustainable future for London" was rejected by the Conservatives and the BNP's only assembly member, Richard Barnbrook.