The electronics engineer who attacked Silvio Berlusconi at a rally in Milan on Sunday believed that the Prime Minister was ruining Italy.

Massimo Tartaglia, 42, who has been kept in isolation after throwing a marble and metal souvenir into Mr Berlusconi’s face, told police that he hated the Prime Minister because “that man is ruining Italy. I don’t agree with anything he says”.

He told police that he had decided to leave the cathedral square “but I heard people shouting, so I went back again. I turned into a narrow side street, I turned round and I saw him just a few steps away from me. He was coming through the barriers. I had a rush of blood to the head. At that point I just wanted to hit him with all my strength. I wanted to make my protest too”.

He added: “I did it all by myself. I am no one’s hitman.”

Doctors said that Mr Berlusconi, 73, would spend a third night in hospital. He lost nearly a pint of blood when his nose was broken. Two teeth were also damaged and he suffered cuts. His treatment is expected to last at least 25 days and he has been told to rest for two weeks. His doctor said that he would not be left with scars.

Mr Tartaglia’s father said that his son was having psychiatric treatment and on antidepressants at the time of the attack. Mr Tartaglia sent a letter to Mr Berlusconi apologising for his “superficial, cowardly and thoughtless action”.

He was not a member of a political party but had told friends and customers in a bar that he could not stand Mr Berlusconi. He bought the model of Milan’s cathedral, which he threw at Mr Berlusconi, from a souvenir stall. Stallholders in the city said that model replicas of the Duomo di Milano, like the one used in the attack, were selling faster than normal.

Mr Tartaglia faces five years in jail or in a psychiatric ward if convicted of assaulting a public official. Former teachers described him as good at computers but said that he had begun to suffer an identity crisis in his final year at school. He enrolled at the Milan polytechnic but left after a few months and joined his father’s company.

In 1995 he was interviewed by national newspapers after inventing Music Pictures, a game in which images change colour in response to different music.

Daniela Insalaco, Mr Tartaglia’s lawyer, told reporters outside San Vittore prison in Milan that she was awaiting a ruling on whether Mr Tartaglia should be sent to a psychiatric unit.

Roberto Maroni, the Italian Interior Minister, told parliament that police believed the attack was premeditated. When asked about reports that police had been warned that Mr Tartaglia was behaving strangely before the attack, he said that members of the public had “simply indicated to the police that there was a mad person disturbing passers-by”.

He said that Mr Tartaglia had been in the Piazza Duomo since 11am — hours before Mr Berlusconi arrived. Despite Mr Tartaglia’s assertion that he acted alone — a claim supported by the Prime Minister’s office — the newspaper Il Giornale said that the attack was part of a conspiracy.

Investigators are due to question Andrea Di Sorte, the youth co-ordinator for Mr Berlusconi’s party, after he told an Italian news agency that he thought that someone behind Mr Tartaglia passed him the souvenir.

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