Rome: An historic Rome square on Sunday turned into a battle field as hundreds of protesters pelted police vans with rocks and bottles and police fired tear gas and water cannon jets into the crowd.

Groups of peaceful protesters could be seen huddling on the steps of St John Lateran basilica for shelter as the battle raged in front of them.

Adding to the chaos, the flow of traffic through the busy hub was not blocked off and cars could be seen driving chaotically through the square.

Stones were thrown at a Ferrari and a Mercedes that found themselves in the midst of the violence. Earlier, hooded protesters set several cars alight and smashed the windows of banks and shops.

"Shame! Shame!" some shouted at police, as others tried to make their way out of police lines around the square with their hands in the air.

"This is disgusting! It's the government's fault for forcing young people to act like this. They've left us without a choice," said Laura, 23.

Nearby another protester, Roberto, said: "It's unbelievable. The police have turned this into a riot. If they just held back we would protest peacefully."

As the man in his 50s said, a group of protesters set light to a police van shortly after its two occupants ran from the vehicle. Between 200 and 300 riot police officers were then seen running from the square.

A female protester was seen staggering from one clash with her face covered in blood. A police spokeswoman said at least four people were injured in the violence, while Italian news agency ANSA reported 20 wounded.

In one part of the square, protesters ripped up paving blocks and threw them at police. Others shouted "No to violence!" and tried to calm the situation