vROME -- A crisis rocking Italy's new government over a decree that lifts the threat of custody from corruption suspects deepened Monday when Prime Minister Silvio Berlusconi was abandoned on the issue by his closest ally.


Gianfranco Fini, leader of the neo-fascist National Alliance, called Berlusconi's stubborn support for the measure untenable and said he would work in parliament to have bribery and corruption restored as offenses liable to pre-trial custody.


"I don't think he (Berlusconi) wants to defend an untenable position," Fini said in newspaper interviews from the United States, where he was watching the World Cup.


Fears that the two-month-old government between media tycoon Berlusconi's Forza Italia party, the National Alliance and the federalist Northern League could collapse over the crisis sent the lira into a tailspin Monday. It broke through the psychological barrier of 1,000 to the mark in the Far East overnight. Government bond prices also dived as operators took fright over the battle of wills between Berlusconi and his coalition allies.


The storm over the measure erupted when the elite pool of "Clean Hands" magistrates in Milan, including national hero Antonio Di Pietro, announced they would quit in protest, saying the decree would hamstring their probes into corruption.


Berlusconi, who has said he stands fully behind the decree, raised the heat on Sunday when he challenged Interior Minister Roberto Maroni to withdraw criticism of the measure or resign.


Maroni, the most senior League minister in the government, has alleged that other members of the cabinet duped him into supporting the decree when it was passed last Wednesday. The League, rejecting Berlusconi's ultimatum, called for the decree to be scrapped and told Maroni to stay put.


"If Berlusconi wants to resign, let him," the League's blunt talking leader Umberto Bossi told reporters. "What he should know, though, is that the minute after he quits, Italy will have a new government."


Berlusconi and his partners powered to triumph in general elections last March as voters dumped a political old guard tarnished beyond redemption by a two-year judicial assault on graft in Italy's Tangentopoli (Bribesville) scandal.


The media magnate has portrayed the decree as a bill of human rights, arguing that the use of preventive detention for a host of crimes in Italy violates fundamental principles.


More than 1,000 suspects remanded in jail for various alleged offenses, have already been released since the decree took effect.


Fini said the decree was fundamentally unjust and that members of the cabinet, including from his own party, had seriously misjudged the mood of the nation. "If someone tells a judge he's corrupt, he goes to jail (for slander), but if he bribes the judge, neither he nor the judge goes to prison. That is intolerable," La Repubblica newspaper quoted Fini as saying.


The decree is valid for 60 days but will not take a place on the statute books unless Parliament approves it.