LONDON (Reuters) - Prime Minister Gordon Brown rejected as baseless and malicious allegations published in a Sunday newspaper that he had terrified staff by shouting abuse at them and in some cases had physically intimidated them. The allegations, contained in excerpts of a new book published in the Observer, put Browns character at the heart of Britains political debate in the build-up to an election due by June that the Labour Party is forecast to lose. These malicious allegations are totally without foundation, said a statement from Browns official spokesman. Brown is the underdog in an election that could end Labours 13-year stint in power as the party struggles to defend its record at a time when Britains economy is in the doldrums and troops are getting killed in an unpopular war in Afghanistan. Labour won the last three elections under former Prime Minister Tony Blair, but Brown is untested at the ballot box: he took the top job when Blair stepped down in mid-term in 2007. Often described as austere, Brown has been trying to show a more sensitive side to voters. He discussed painful and intimate details of his life in a television interview a week ago. A YouGov opinion poll published in the Sunday Times suggested the strategy was working: Labour was up 3 percent month-on-month, at 33 percent. That was 6 points short of the opposition Conservatives; the narrowest gap in months. However, the poll was conducted before the publication of excerpts from a new book by Observer political columnist Andrew Rawnsley, whose tales of volcanic temper tantrums by Brown immediately shot to the top of the political agenda. Among other allegations, Rawnsley wrote that during fits of rage Brown had screamed at staff, grabbed one aide by the collar of his shirt, and thumped his fist into a car seat, causing another aide to cower in fear of being hit in the face. Brown has not responded to the specific allegations made by Rawnsley, but just before the excerpts were published he defended his character, saying he had never hit anybody. If I get angry, I get angry with myself, Brown said on Saturday in an interview with Channel 4 television. I dont do these sorts of things, he said, looking pained. In separate comments to the Independent on Sunday, Brown tried to make light of the allegations. I may have done one or two good tackles at rugby, but the idea that is suggested in this so-called inside account is just ludicrous, he was quoted as saying. Rawnsley strongly defended his book, saying that it was based on detailed conversations with impeccable sources. The Conservatives did not seem inclined to seize on the allegations for a Brown character assassination, though there were barbed comments from William Hague, a senior figure. I dont think hes ever really shown that he can lead a happy and successful team, and maybe if theres truth in any of these allegations thats part of the reason why, he said. But the main reason we should decide to have a change of government is because of the bigger issues, he told Sky TV. Brown allies including Business Secretary Peter Mandelson and other senior ministers lined up to defend him. Mandelson said Brown was very demanding of himself and of colleagues. He knows what he wants to do. He does not like taking no for an answer from anyone. He will go on and on until hes got a policy or an idea in the best possible form which he can then roll out, Mandelson said in an interview on BBC television. On the way, yes, there is a degree of impatience about the man, but what would you like, some sort of shrinking violet at the helm of the government when were going through such stormy waters? he said.