Berlusconi: They're all out to get me
In a series of fierce outbursts, he presented himself as a martyr for democracy and warned that civil liberties would be trampled on if his rival, Romano Prodi, won the ballot on Sunday and Monday.
However, centre-left opposition leaders accused him of losing his nerve in the face of a likely election defeat.
A furious-looking Mr Berlusconi told a news conference that mainstream Italian newspapers, backed by major industrialists, were working to undermine his campaign. He also accused Milan magistrates of deliberately trying to wreck his political ambitions by seeking to press charges against him ahead of the election. "There are state employees whose salaries came from the citizens and who plot, plot and plot against the prime minister," he said.
Later, he said United Nations observers should monitor the election. "With all the newspapers on [the Left's] side, with television stations behaving the way you've seen, you bet they should come to defend us from these men who are experts at rigging [elections]," he said.
Mr Berlusconi has dominated the acrimonious election campaign with a string of pledges, outbursts and gaffes that have turned the vote into a referendum on himself. But he has appeared increasingly tense in recent days and opposition leaders said he was losing his calm.
"Berlusconi is a man who is fighting against the entire country. I don't know how he can think to govern Italy in this fashion," Massimo D'Alema, a former prime minister and chairman of the largest opposition party, the Democrats of the Left, said. "In fact, I don't think he is going to govern it any more."
On Wednesday, Mr Berlusconi was forced to pull out of a prime-time interview on one of his own Mediaset television stations following an avalanche of protests from opposition politicians.
Much of his anger has been aimed at prosecutors who want him to stand trial on charges of bribing lawyer David Mills - the estranged husband of Tessa Jowell, the Culture Secretary. Mr Berlusconi has always denied bribing Mr Mills and yesterday he presented bank statements that he said proved the money in question had come from a Naples shipbuilder.
The prime minister's coalition has trailed the centre-left in opinion polls for the past two years, as voters signal their discontent with an economy that has barely grown since 2001. An opinion poll blackout came into force two weeks ago, at which point the opposition was ahead by between 3.5 and 5 percentage points.
Mr Berlusconi told a rally of his Forza Italia party on Wednesday that he had finally taken the lead, but critics said he was bluffing. And for the first time yesterday, he talked about the possibility of defeat.
"Even if I were defeated, which I don't think will be the case, it will be a very limited defeat and the Left will have to take account of us in parliament," he said.