Evidence emerged that the assault early on Sunday morning, in which 61 people were injured, had been a vendetta by police officers seeking revenge for the rioting at the G8 summit.

Last night the parliamentary opposition demanded a commission of inquiry into the policing of the summit and the resignation of the interior minister, Claudio Scajola.

In a raucous debate, Mr Scajola and the prime minister, Silvio Berlusconi, tried to distance themselves from the raid on the headquarters of the Genoa Social Forum.

To guffaws of disbelief, they insisted that they did not know in advance that 200 police officers would attack the forum. More than a dozen of the 93 people arrested were carried out on stretchers.

"A pack of lies, responded Vittorio Agnoletto, a spokesman for the forum. "It was authorized butchery."

Political analysts questioned the government's claim that the head of the police force, Gianni De Gennaro, would have given the order without consulting the interior minister.

The forum has called for protests at police stations throughout the country today against what it called vicious, deceitful tactics.

An anarchist website warned of violent revenge for the death of Carlo Giuliani, 23, who was shot by police.

A letter bomb exploded in Verona, causing no injuries. Another device sent to Genoa's prefect was intercepted and defused.

For the duration of the raid Italy had been a state without law, said Fausto Bertinotti, leader of the Refounded Communists. "In these days things have happened which in my life I have never seen - never."

An interior ministry source admitted that the raid had turned into a revenge attack by police venting their frustration after two days of failing to control looting and thuggery.

Officially the operation has been called a success. The officers who stormed the two schools in which the forum had its headquarters found two Molotov cocktails, a nail bomb, two sledgehammers, a pickaxe and 12 penknives.

The 93 who were arrested may be charged with criminal association, possession of explosives, resisting arrest and damage to public property.

A forum spokesman said the sledgehammers and pickaxe, which were covered in dust, had been left by workmen who had not yet finished building the school.

The knives were needed to open tins of food, and the homemade bombs were probably planted, he added.

But yesterday magistrates questioned why the carabinieri, the police force which is part of the army, had used inexperienced teenage conscripts.

The intelligence services allegedly terrified the conscripts with warnings that packets of HIV-infected blood infected would be thrown.

A cameraman said that protesters, fearing police ambushes, begged television crews to escort them to the railway station.

But the protesters may have lost the public relations battle. An opinion poll by Datamedia suggested that most Italians believed the police were too tolerant.

© Guardian Newspapers Limited 2001

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