A top Italian court on Wednesday overturned a law granting Premier Silvio Berlusconi immunity from prosecution, allowing prosecutors to resume a corruption trial that could increase pressure on him to resign.

A spokesman said the billionaire businessman-turned-politician would not step down.

"Berlusconi, the government and the majority will continue to govern," Berlusconi spokesman Paolo Bonaiuti said, calling the ruling "a political verdict."

The Constitutional Court's 15 judges overturned the law that caused the suspension of a trial in which Berlusconi was charged with ordering the 1997 payment of at least $600,000 (euro408,329.93) to British lawyer David Mills in exchange for the lawyer's false testimony at two hearings in other corruption cases in to the 1990s.

The 2008 law was passed by Berlusconi's conservatives while the premier was on trial in Milan.

The legislation also shielded the president of the republic and the two parliament speakers from prosecution. Berlusconi's trial was suspended as a result of the law and opponents charged the law was tailored to protect the premier.

Berlusconi denied the corruption charges, and his lawyers have argued in court on Tuesday that he could not be a defendant and at the same time serve as premier.

The Constitutional Court said in a statement that after two days of deliberations it had found that the law violated the principle that all are equal before the law.

It rejected it on formal grounds because it was not passed with the lengthy procedure that must be used for any law concerning the constitution.

The law is an amended version of earlier legislation that was rejected by the Constitutional Court in 2004.

While Berlusconi's portion of the trial was frozen when the immunity bill was passed, the proceedings continued for Mills. In February, he was convicted of corruption and sentenced to 4 1/2 years in prison. Mills, the estranged husband of Britain's Olympics Minister Tessa Jowell, has maintained his innocence and said he would appeal.

Berlusconi had been acquitted or cleared in previous trials on various charges because the statute of limitations had expired.