Those arrested, who include an Italian teenager, will be charged with setting fire to rubbish bins and tires, blocking the public highway and possession of dangerous objects, police said.

The anti-G8 group, which included foreigners, briefly blocked a road turnoff in a Rome suburb leading to the motorway that links the Italian capital to L'Aquila, the Abruzzo city hosting the July 8-10 summit.

Police said they were still weighing charges against the 36 people who were detained.

There was also tension at Rome's Roma 3 University where demonstrators threw bottles, stones and smoke bombs at police but clashes were averted and no one was arrested.

In L'Aquila, police and soldiers swept the area around the summit venue. Five French men were prevented from pitching a tent after police said they found metal sticks and a bat in their van.

The five, aged between 25 and 35, were not arrested as police were unable to press weapons charges.

But the men were told to stay out of the province of L'Aquila.

Meanwhile demonstrations swept Italian universities against Monday's arrest of 21 students who were involved in protests at a G8 'universities summit' in Turin in May.

The 21 anti-capitalist militants are accused of attacking police with stones, metal clubs and firecrackers.

University students staged demos and sit-ins in Venice, Milan, Genoa, Bologna, Rome, Naples, Cagliari and Palermo. Italy's various 'No Global' groups and freedom of speech bodies also protested the arrests Tuesday, accusing the government of trying to muzzle opposition.

Italy is on high alert to prevent a recurrence of the unrest that marred Italy's last G8 summit, in Genoa in 2001.

Scores of police, soldiers and anti-terrorism units will guard the converted police barracks where the G8 leaders will meet.

The city will also be protected by an 'air shield' of high-tech radar systems and fighter planes.

Interior Minister Roberto Maroni said representatives of foreign countries had been so impressed by the security arrangements that they had asked for details on how to replicate them.

''We've done everything we had to do...I'm proud,'' he said.