Italian Prime Minister Silvio Berlusconi was jointly responsible for corruption by his Fininvest company in a 1990s battle to buy publisher Mondadori, a judge said in arguments for imposing damages on the firm.

Silvio Berlusconi is co-responsible in the corruption issue ... as a logical consequence (of) the principle of civil responsibility as head of the company, said the court document explaining the decision which Reuters obtained on Monday.

There was no immediate comment from the prime minister's office.