Guido Bertolaso, head of the civil protection agency and an aide to Italian Prime Minister Silvio Berlusconi, resigned on Wednesday over a probe into contracts for the original site of last year's G-8 summit, his office said.

Bertolaso, 59, resigned after police searched the office of the civil protection department in Rome and handed him an official notice that he was formally under investigation.

The probe involved construction on the Sardinian island of La Maddalena.

Bertolaso said in a statement he would cooperate with investigators and handed his resignation to Berlusconi "so as not to be an obstacle to the investigation."

Hundreds of millions of euros were spent on preparing the site for last July's G-8 summit but the meeting was moved to the central city of L'Aquila, which was hit by an earthquake the previous April.

Four people were arrested on Wednesday in relation to the same probe. One of them was Angelo Balducci, who is on the board of Italy's public works department, a different government agency.

Reuters