Italy's lower house parliament was set to vote later Thursday on whether to authorise a police search of the offices of Silvio Berlusconi's accountant for documents allegedly detailing payments made to prostitutes on behalf of the premier, according to dpa. The request stems from an investigation by prosecutors in Milan who accuse the Berlusconi of involvement underage prostitution and abuse of power. Accountant Giuseppe Spinelli is suspected of compensating with cash and gifts, dozens of women who attended alleged sex parties at the premier's residences. Berlusconi, as a member of parliament, enjoys immunity from arrest or searches in criminal probes, unless parliament decides otherwise. Despite the ruling conservative coalition's slim majority in the Chamber of Deputies, Justice Minister Angelino Alfano said he was confident the request would be denied. Berlusconi has maintained he has never paid for sex and also that he did not know that the woman at the centre of the underage prostitution allegations, Moroccan go-go dancer Karima El Mahroug, was only 17 years old when he met her. But opinion polls suggest the scandal has slashed his approval ratings and prompted criticism of the premier from the country's influential Catholic Church.