Politicians in Italy have blamed a hard core of Lazio and Roma fans for the riot that caused Sunday’s Rome derby to be abandoned.

Police said they had arrested 18 supporters from both sides, some of them known hooligans, after a six-hour battle between police and fans that left more than 170 people injured.

Some politicians attributed the violence to a remark made by the prime minister, Silvio Berlusconi, a day earlier. Berlusconi suggested that “revolution would explode” on the terraces if the government did not help out Italian football, which is £341m) in debt.

“It seems to me like an operation aimed at blackmailing the government,” the welfare minister Roberto Maroni said.

Violence broke out when a false rumour circulated that a boy had been killed by a police car outside the Olympic Stadium.