By Catherine Hornby
ROME (Reuters) - Hundreds of hooded demonstrators clashed with police in some of the worst violence in the Italian capital for years on Saturday, setting cars on fire and breaking shop and bank windows.
Police repeatedly fired teargas and water cannons in attempts to disperse them but the clashes with hard-core demonstrators continued hours after tens of thousands of people in Rome joined a global "day of rage" against bankers and politicians.
Discontent is running high in Italy over high unemployment, political paralysis and 60 billion euros ($83 billion) of austerity measures that have raised taxes and the cost of health care.
The violence at times resembled urban guerrilla warfare as protesters hurled rocks, bottles and fireworks at police, who responded by repeatedly charging the demonstrators.
At least two demonstrators were injured and one was reported to be in critical condition. At least 30 policemen were injured.
At one point demonstrators surrounded a police van, pelted it with rock and bottles, and set it on fire. The two occupants managed to escape, television footage showed.
Rome mayor Gianni Alemanno ordered all public museums in the capital closed for security reasons as the violent demonstrators continued to run amok hours after the protest began.
The demonstration began peacefully but suddenly turned violent when hundreds of hooded radicals known as "black blocs," who had infiltrated the group, set cars and garbage bins on fire.
They then went on a rampage on several streets around the Colosseum, trashing windows of stores and banks.
One building, believed to be an annex of the Defense Ministry, caught fire after the flames spread from a car.
The protesters had earlier forced their way into the annex and trashed the offices.
The protest was one of many staged around the world on Saturday to show solidarity with the Occupy Wall Street movement in the United States, venting anger over years of economic and financial crisis since a global credit boom went bust in 2007.
Italy's fractious coalition government has been forced to push through austerity measures to try to stop the economy -- the euro zone's third largest and one of its heaviest debtors -- from being sucked into the bloc's debt crisis.
Hours after the demonstration began police were still firing teargas canisters and training water canon on violent demonstrators in Piazza San Giovanni, the terminus of the demonstration, where a final rally was due to be held.
Masked demonstrators attacked police vans with rocks, bottles and clubs in the San Giovanni area, which was full of tear gas.
Some of the peaceful demonstrators tried to take refuge on the steps of St. John's Basilica, one of the largest churches in Rome and Pope Benedict's basilica in his capacity as bishop of Rome.
The streets of central Rome were littered with rocks, bottles and garbage bins that had been overturned in the protest and fire brigades drove around the city trying to put out the fires.
Peaceful demonstrators also clashed with the militants and turned some of them over to police.
Politicians across the political spectrum condemned the violence.
"Unacceptable violence and devastation is happening right now on the streets of Rome," said Pierluigi Bersani, head of the Democratic Party, the largest in the opposition.
"Those who are carrying out what is nothing less than urban guerrilla warfare are hurting the cause of people around the world who are trying to freely express their discontent with the world economic situation," he said.
Alemanno, noting that the demonstrators had called themselves "the indignant ones," said: "Those who are really indignant are the citizens of Rome."
(Writing by Philip Pullella; Editing by Ruth Pitchford)