A Milan judge yesterday suspended the high-profile trial of US and Italian agents suspected of a CIA kidnapping after Prime Minister Silvio Berlusconi authorised witnesses to invoke state secrecy.

Judge Oscar Magi said Mr Berlusconi had made it extremely difficult to know what evidence should be allowed in the trial of 26 Americans and seven Italians accused of kidnapping a terrorism suspect in Milan in 2003.

Judge Magi suspended the trial until March next year, when a higher court is expected to rule on the government's request to dismiss the case entirely. The government says it should be thrown out because prosecutors violated state secrecy rules.

Prosecutor Armando Spataro, in some of his strongest language yet, accused Berlusconi and former Prime Minister Romano Prodi of obstruction.

"I understand the defence lawyers' aspirations to interpret state secrecy as a path to impunity or to prevent the discovery of the truth... it is the same (as) the current and previous prime ministers, to use state secrecy to obstruct justice," Mr Spataro said.

The spies are accused of seizing a terrorism suspect, Hassan Mustafa Osama Nasr, in broad daylight on the streets of Milan and flying him to Egypt, where he says he was tortured and held for years without charge. The Americans, almost all of whom are believed to working for the US Central Intelligence Agency, are being tried in absentia.

Human rights groups have accused the United States of breaking international law and "outsourcing torture" by secretly transferring people to other countries in operations known as extraordinary renditions.

Washington denies the torture charge but has defended renditions as a valid counter-terrorism tool that has produced vital intelligence.

Mr Berlusconi, who denies the Italian government knew anything about a kidnap plot, wrote in a letter to the court last month that it was free to hear evidence on the abduction itself.