The law granting him immunity from prosecution has been lifted but Berlusconi insists forthcoming trials will not oust him

The Italian prime minister, Silvio Berlusconi, has insisted he will stay in office even if he is convicted in one of the trials in which he is a defendant.

After a summer of sex scandals and legal wrangling, Berlusconi faces two trials, following a decision by the country's top court to lift his immunity from prosecution and allow proceedings against him to resume.

In one case, due to start on 16 November, he is accused of tax fraud and false accounting in the management of his media companies. In a separate trial, whose next hearing is due on 27 November, Berlusconi is charged with paying a $600,000 (£363,121) bribe to British lawyer David Mills to withhold incriminating details of his business dealings.

"I still have faith in the existence of serious magistrates who hand down serious verdicts, based on facts," said Berlusconi, according to excerpts of a forthcoming book that were released yesterday. "If there were a conviction in trials like these, we would be facing such a big subversion of the truth that I would feel even more duty bound to stay in my post to defend democracy and the rule of law."

Berlusconi has been in defiant mood since Italy's constitutional court ruled last month that his protection from prosecution while he holds office violated the constitution. The ruling overturned a law that critics had denounced as tailor-made to protect him from his legal woes. Since then, he has repeatedly attacked the judicial system as overrun by "communist" magistrates out to destroy him.