Protestors clash with police during the Occupy demonstration in Rome. Photograph: Guido Montani/EPA
Economic protests inspired by Spain's "Indignants" and the Occupy Wall Street movement in New York spread to cities around the world on Saturday. Tens of thousands went on the march in London, Frankfurt, Madrid, Rome, Sydney and Hong Kong as organisers aimed to "initiate global change" against capitalism and austerity measures. Rallies were expected in 82 countries.
As dusk fell on more than 2,000 protesters assembled in front of St Paul's Cathedral in London, earlier addressed by the WikiLeaks founder Julian Assange, New York was bracing itself for a takeover ofTimes Square in a continuation of the Occupy Wall Street protests. Manhattan has seen a regular encampment of protesters in Zuccotti Park and violent clashes with police and officials.
There was civil unrest in Rome, where police turned teargas and water cannon on the crowds. Smoke hung over Rome as a small group broke away from the main demonstration and smashed windows, set cars on fire and assaulted television news crews. Others burned Italian and EU flags. "People of Europe: Rise Up!" read one banner in Rome. Fights broke out and bottles were thrown between demonstrators as some tried to stop the violence.
In London, police made seven arrests and kept the crowd "kettled" near St Paul's. Assange made a dramatic appearance, bursting through the police lines just after 2.30pm, accompanied by scores of supporters. To clapping and some booing, he climbed the cathedral steps to condemn "greed" and "corruption". In particular he attacked the City of London, accusing its financiers of money laundering and tax avoidance. "The banking system in London is the recipient of corrupt money," he said, adding that WikiLeaks would launch a campaign against financial institutions.
Assange is on bail as he fights extradition to Sweden, where he is wanted for questioning over claims of rape and sexual molestation made by two women.
Among the protesters there was a sizeable presence from Spain, home of the "Indignant" movement. Media student Sergio, 27, said he hoped London would copy protests in Madrid, where camps have been set up for weeks at a time. "Initially there were only three tents, but when the police kicked them out hundreds followed. I hope we see the same here," he said.
By mid-afternoon seven tents had been erected in bright sunshine outside St Paul's. Audrey Versteegen, 27, from Manchester, owned one. "I will stay here as long as possible," she said.
Assange aside, perhaps the strangest event of the day came when a bride arrived at the side-chapel in St Paul's. Across the road, scores of police were changing into riot gear as she entered the cathedral. It was clear that Scotland Yard had opted for pre-emptive strong-arm tactics in the wake of the summer riots. Last week the new Met commissioner, Bernard Hogan-Howe, had pledged to "win days of action".
In Germany, about 4,000 people marched through the streets of Berlin, with banners calling for an end to capitalism. Some scuffled with police as they tried to get near parliamentary buildings. In Frankfurt, continental Europe's financial capital, some 5,000 people protested in front of the European Central Bank.
In the Bosnian city of Sarajevo, marchers carried pictures of Che Guevara and old communist flags that read "Death to capitalism, freedom to the people".
Another 500 people gathered at a peaceful rally in Stockholm, holding up red flags and banners that read "We are the 99%" – a reference to the richest 1% of the world's population who control its assets while billions live in poverty.
"There are those who say the system is broke. It's not," trade union activist Bilbo Goransson shouted into a megaphone. "That's how it was built. It is there to make rich people richer."
A protest was due to begin in Lisbon and six marches were expected to converge on Madrid's Puerta del Sol plaza. Asian nations, where the fallout from the banking crisis has been less severe, saw less well attended protests – 100 turned out in the Philippines.
A group of 100 prominent authors including Salman Rushdie, Neil Gaiman and Pulitzer prize-winning novelists Jennifer Egan and Michael Cunningham signed an online petition declaring their support for "Occupy Wall Street and the Occupy movement around the world".