By David Willey
BBC correspondent in Rome
Silvio Berlusconi accuses the judiciary of a political vendetta
Exactly four weeks before Italians go to the polls to elect a new government, the country's prime minister for the past five years, Silvio Berlusconi, who is running neck and neck in a close-fought election campaign against his political opponent Romano Prodi, has suffered a significant political setback.
He learned that on 11 April, the day after the election - whatever the result of the vote - he may find himself sent for trial later this year by a Milan judge on bribery and corruption charges relating to his business dealings before he went into politics a decade ago.
He also learned that he had lost a senior cabinet minister, Francesco Storace, who announced his resignation from the governing centre-right coalition in the wake of an unrelated wire-tapping scandal.
This was the second ministerial resignation suffered by Mr Berlusconi in the run-up to this election.
Mr Berlusconi has repeatedly accused the Milan judges of left-wing political bias.
He claims that for years they have been carrying out a systematic vendetta against him and the media empire that he and his family control, accusing him of corruption, tax cheating, and fraud.
He has always protested his innocence.
Conflicts of interest
"Once again, and just before the elections, certain lawyers are voluntarily giving up the search for truth to pursue political goals," commented Sandro Bondi, national coordinator for Mr Berlusconi's Forza Italia political party.
In at least six previous corruption cases which did go to trial, Mr Berlusconi was either acquitted by a court of first instance or on appeal, or, crucially, when proceedings came to a halt through statutes of limitations.
It is Mr Berlusconi's involvement in every part of Italian life that angers his critics, and exasperates his rivals
Mr Berlusconi has always been able to afford top lawyers, and during his period in office as prime minister has managed to make important legislative changes which have favoured his personal business interests.
Although he has handed over the daily running of his business empire to his children and his business associates, he is still the beneficial owner of one of Italy's biggest business fortunes.
Although he promised that if elected prime minister he would address perceived conflicts of interest between his private business and his public roles, he has never done so in a manner which has satisfied his critics.
The latest corruption case involving the prime minister concerns an investigation by Milan prosecutors into alleged fraud and corruption committed by Mr Berlusconi in connection with the purchase of American film rights for his media group Mediaset.
The prosecutors believe that the price of these rights was artificially inflated by intermediary companies in order to set up offshore slush funds to pay off politicians.
The British corporate lawyer David Mills helped Mr Berlusconi to set up offshore companies and tax-haven bank accounts for his holding company Fininvest and its many subsidiaries.
He also now faces possible indictment for having given false evidence to prosecutors investigating the labyrinthine accounts of Mr Berlusconi's media empire.
Mr Berlusconi is one of Italy's wealthiest businessmen.
His fortunes were founded on real estate speculation and the accumulation of commercial television channels which gave him a virtual monopoly over commercial TV broadcasting in Italy.
A special law authorising him to break the previous TV monopoly of the state-run RAI, was passed by parliament during the 1980s with the help of Mr Berlusconi's close friend, the former Prime Minister Bettino Craxi, head of the now defunct Socialist party.
Mr Craxi was later convicted in absentia on corruption charges by the Italian courts, but he had already fled into exile in Tunisia where he died in 2000.