Silvio Berlusconi refused again yesterday to concede defeat to Romano Prodi's centre-left coalition in the Italian election, demanding the formation of a broad coalition in a letter that commentators said amounted to a request by the media mogul for immunity from prosecution.

"On the basis of the popular vote, there's no winner and no loser," Mr Berlusconi claimed in the letter to the Corriere della Sera. Hours earlier, the premier had said he still hoped he would be declared the winner, as long as the count of contested ballots continued. He renewed an appeal to create a coalition government, "limited in time and aimed at dealing with the country's institutional, economic and international commitments".

Mr Prodi's Union coalition has slender majorities in both houses of parliament after the roller-coaster election divided Italy almost in two a week ago. But this is not just a case of Mr Berlusconi being a bad loser, say pundits. During his five years in office he spent much of his time passing laws to avoid going to jail. Many commentators believe Italy's richest man wants to gain an informal pledge of immunity from judicial proceedings from Mr Prodi's government, in return for a guarantee that his Forza Italia party will not make political life unbearable for a fragile administration.

Mr Berlusconi's proposal in the Corriere was a plea for "a grand coalition to save himself", said Valentino Parlato, the veteran editor of the maverick left-wing Il Manifesto newspaper. Mr Parlato urged leftist voters to exercise "democratic vigilance" against the skulduggery he believes the centre-right may employ to try to snatch back victory.

President Carlo Azeglio Ciampi might decide to give Mr Prodi a mandate to form a new government early next month, so as to end the uncertainty caused by Mr Berlusconi's antics, political sources said. The tycoon does not have to resign formally as Prime Minister until 29 April and in theory could remain in office as a mischievous caretaker until early June.

Mr Berlusconi has alleged irregularities in the vote of Italians abroad, which proved key in swinging the Senate. "Threatening to invalidate the elections and a grand coalition to save himself are two equally dangerous and subversive scenarios," Mr Parlato said. "It could equally be an opportunity for a national emergency, a nasty terrorist attack, an opportunity or necessity for everyone to stick together to safeguard the fatherland."