Berlusconi has frequently accused judges of bias

The spokesman, Sandro Bondi, proposed setting up an inquiry commission to investigate whether parts of the judiciary were operating with what he described as subversive ends.

On Wednesday, a court in Milan said the trial earlier this year of a close associate of Mr Berlusconi, Cesare Previti, brought to light the largest corruption case in Italy's post-war history.

There are avalanches and truck-loads of elements coming from the history of the last 10 years which demonstrate that there is judicial persecution against the prime minister Sandro Bondi Berlusconi spokesman

Mr Previti, who was sentenced to 11 years in prison, says he was a victim of left-leaning magistrates.

Mr Berlusconi, who was on trial earlier this year accused of bribing judges, has also frequently described the judiciary as being biased against him.

The ruling coalition pushed a law through parliament in June granting the prime minister and other top officials immunity and halting the trial.

Disbelief

Mr Bondi said the new commission would be proposed to parliament in September.

"There are avalanches and truckloads of elements coming from the history of the last 10 years and these last few days which demonstrate, beyond any doubt, that there is judicial persecution against the prime minister," he said.

Members of the judiciary appeared shocked by Mr Bondi's statement.

"I cannot believe this proposal," Italian radio quoted Virginio Rognoni, deputy chairman of the Higher Council of the Judiciary, as saying.

There were also doubts from within the ruling coalition itself.

Christian Democrat MP Luca Volonte said his party would not support the proposal if it affected current trials.