The governing body of Italian magistrates, the CSM (Consiglio Superiore della Magistratura), is set to rule that a decree being pushed through Parliament by the centre Right government of Silvio Berlusconi suspending "non priority" trials for a year is "unconstitutional".

The decree, which critics of Mr Berlusconi say is designed to halt a trial in Milan in which he accused of corruption together with David Mills, the estranged husband of Tessa Jowell, the Olympics Minister, has been approved by the Senate and is guaranteed passage in the Lower House, where Mr Berlusconi has a commanding majority.

A draft resolution drawn up by the CSM says the measure would freeze "over half the trials currently under way", and amounts to an "concealed amnesty". It was "irrational and arbitrary" and would have "gravely negative effects" on the system of justice as well as causing "social alarm" by letting off criminals. The resolution is expected to be approved by the CSM ruling council.

Elio Vito, Minister for relations with Parliament, said a separate draft law giving the holders of the top offices of state - including Prime Minister - immunity from prosecution would be tabled in Parliament "before July".

In a vehement and at times intemperate attack on the magistrates at a conference of the Italian shopkeepers association Mr Berlusconi called the Italian judiciary a "cancerous growth", claiming biased prosecutors had pursued him since he entered politics 14 years ago. Crossing his wrists as if in handcuffs, Mr Berlusconi said: "Many prosecutors would like to see me like this."

However to his evident surprise he was whistled and booed by association members, who normally form part of his natural constituency and power base. He said he had spent €174 million on legal fees in a series of cases linked to his business empire, which ranges from Italy's commercial television network to AC Milan. He rejects the charge that his troubles stem from the "anomaly" of a business tycoon also being Prime Minister.

In a sign of Church concern the Catholic magazine Famiglia Cristiana this week accused him of being "obsessed" with a hatred of magistrates. The controversial decree is intended to crack down on crime and reform the judicial system, but the Prime Minister's critics say he is abusing his power by using it to get himself off the hook.

The row has all but destroyed the post-election bipartisan dialogue between the government and the centre-Left opposition, whose leader Walter Veltroni called Mr Berlusconi's outburst "embarrassing".President Napolitano said he was concerned that the controversy was "rekindling a dangerous rivalry between politics and justice".

Referring to himself in the third person, Mr Berlusconi insisted that from 1994 to 2006 "789 prosecutors and magistrates took an interest in the politician Berlusconi with the aim of subverting the votes of the Italian people". He said he was "indignant" at being accused of passing laws to benefit his own interests, and repeated that he would not use the new decree to suspend the Milan trial, in which he is accused of giving Mr Mills a 600,000 dollar bribe to give misleading evidence in earlier corruption trials in the 1990s. Both men deny the charge.

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