Around two hundred people, mainly police officers, were injured as officers clashed with masked protesters at a rally against a high-speed rail link in northern Italy yesterday, police said.

Clashes between protesters and police left at least 188 officers and about a dozen demonstrators hurt, said officials, after a small group stormed a tunnel which was part of the work site at Chiomonte, west of Turin.

Scuffles between protesters and a heavy police presence continued throughout the day, with a steady exchange of tear gas, stones and molotov cocktails.

Police arrested at least five people and Italy’s President Giorgio Napolitano condemned the violence.

Police blamed the trouble on hundreds of masked leftist “black block” extremists from Italy and neighbouring countries.

Protest organisers said tens of thousands of demonstrators had gathered peacefully from surrounding regions to stop the construction of the planned tunnel in the Susa valley.

But a small band broke away from the main group of protestors to enter the gated work site guarded by hundreds of police, who put the number of demonstrators at about 6,000.

The project, agreed by Italy and France in 2001, would slice three hours off the current seven-hour train journey between Paris and Milan. But the development has provoked fierce opposition, not least among 23 local mayors.

In a statement, President Napolitano condemned what he said was the work of groups “trained in illegal violence.”

He was joined by Prime Minister Silvio Berlusconi and figures across the political spectrum.

Police were out in force yesterday as authorities had expected more trouble from radical groups within the protest movement after similar clashes last week.