More than 50 leading economists have signed a letter attacking the plans of the opposition Conservatives as party leaders prepared for Britain's first ever presidential-style TV debate on Thursday. Academics from Britain, the US, Germany, Australia and Canada warned that spending cuts proposed by David Cameron's party risked tipping the country 'back into recession,' in a letter obtained by The Daily Telegraph newspaper. The letter signed by 58 academics comes more than two weeks after a rival letter signed by some of Britain's most senior businessmen, which backed Cameron's tax plans. The economy is the central issue of the May 6 general election, in which the Conservatives are seeking to prevent Prime Minister Gordon Brown's Labour Party from winning a fourth term in office. Britain only crawled out of its worst recession since World War II at the end of last year. The letter said the Conservatives' proposal to reduce public spending by six billion pounds (nine billion dollars, seven billion euros) in a bid to reduce Britain's massive public deficit could 'lead directly to job losses.' 'The main opposition party now proposes to cut an extra six billion pounds, on top of the measures already planned by the government,' said the letter. 'The cut is described as efficiency savings. But in macroeconomic terms it is just a cut by another name. It will lead directly to job losses and indirectly to further falls in spending.' It added: 'At a time when recovery is delicate it could even affect confidence to the degree that we are tipped back into recession.' Signatories of the letter include David Blanchflower, a former member of the monetary policy committee, and Richard Layard, emeritus professor of economics at the London School of Economics (LSE). Peter E. Earl, Associate Professor of Economics at the University of Queensland, Australia, is among the foreign academics to have put his name to it. The Conservatives have said they will scrap a proposal by the Labour government to hike payroll taxes known as National Insurance, which is paid by both employers and employees. The letter will be a welcome boost to Brown ahead of the first of three TV debates Thursday, where he will face Cameron and Nick Clegg, leader of the Liberal Democrats, the third-biggest party. The debates, the first of their kind ever to be held in Britain, could make or break the election hopes of each man and particularly Cameron, who is tipped to make the strongest performance. The Conservatives have seen a strong lead in opinion polls melt away in recent months and most surveys now show a hung parliament is the most likely outcome. The debates are subject to 76 rules hammered out in painstaking negotiations between broadcasters and the political parties. The subject of Thursday's is domestic politics, with foreign policy next week and the economy in the third week. The format is expected to allow no more than eight or nine questions over the 90-minute programme to be shown on ITV. Brown is said to have struggled in rehearsals for the debates, giving answers that run far beyond allowed time limits or reverting to reciting lists of statistics. Cameron has admitted he is 'tense but optimistic' about the debate. 'I can't say I'm not nervous,' he said during campaigning Wednesday. 