The Italian Senate has approved a new decree which critics of Silvio Berlusconi, the Prime Minister, say is "tailor made" to save him from a possible prison sentence for corruption.

Mr Berlusconi claims his "security package" fulfils a campaign promise he made in April's election to crack down on crime, and denies it will apply to his own case. It now passes for a final vote to the Lower House, where he has a commanding majority and approval is a formality.

However, Italy's centre-left opposition claimed the main purpose of the decree was to help Mr Berlusconi evade corruption charges. A key clause suspends for a year trials for alleged crimes committed before mid-2002, with the exception of those involving violence, Mafia-related offences, and those carrying a jail sentence of more than 10 years.

Mr Berlusconi and his supporters say this is aimed at overhauling Italy's overburdened judiciary and clearing a trial backlog. A recent opinion poll in La Repubblica showed only 35 per cent of the public have faith in the notoriously slow and inefficient Italian judicial system.

However - in a development which the Prime Minister's opponents say is far from coincidental - the decree will also serve to freeze an ongoing trial in Milan in which Mr Berlusconi is accused of ordering payment in 1997 of some $600,000 to David Mills, the estranged husband of the Olympics Minister Tessa Jowell, in exchange for allegedly "misleading" testimony by Mr Mills at two Berlusconi corruption trials in the 1990s. Both men deny the charges at the trial, which is close to reaching a verdict.

Anna Finocchiaro, Senate whip for the centre-left Democratic Party, accused Mr Berlusconi of "endangering democracy" by pushing through "ad personam" laws to his own benefit, as he did in his last period in power from 2001 to 2006.

However, Niccolo Ghedini, Mr Berlusconi's lawyer, who is also one of his party deputies, denied that the Prime Minister was aiming to have his trial suspended. "He has said the trial will go ahead," Mr Ghedini told a press conference at the Foreign Press Club.

Mr Ghedini added that, even if Mr Berlusconi asked for the trial to go ahead, Mr Mills could benefit from the decree by asking for a year's suspension, at which point their trials would be separated.

However if a further, proposed law granting heads of state immunity from being prosecutued was then passed, Mr Berlusconi could not then be prosecuted while in office, whereas Mr Mills's trial would resume after a year, Mr Ghedini said.

Mr Berlusconi has long been paranoid about the influence of "subversive" left-wing magistrates, who he accuses of holding against him a political vendetta. Last week, his lawyers asked for the removal of the Milan trial's presiding judge, Elisabetta Gandus, saying she was openly biased against him. The request was turned down.

His law and order package also includes the deployment of 3,000 troops onto the streets of Italian cities to help police combat rising street crime, including robberies and murders, a third of which are committed on illegal immigrants, according to the Interior Ministry. The army is also to be used in Naples to help solve the rubbish crisis by guarding newly opened landfill sites against local protesters.

The National Association of Magistrates said the trial-freezing measure would cause "unprecedented chaos". It said: "Whoever governs the country cannot insult and delegitimize the judicial system when his personal interest is at stake."

The popular Roman Catholic magazine Famiglia Cristiana accused Mr Berlusconi of being "obsessed" with being persecuted by so-called left-wing magistrates who in reality were doing their duty. It said he was placing his "personal obsessions" above the interests of the country.

Times Recommends

• Michael Jackson: Not the final chapter
• Indian Army spends10m rupees on golf buggies
• Brüno toned down for 15 rating