Anti-capitalist protesters in London were continuing their demonstration through the night after the movement that began with Occupy Wall Street spread worldwide.
Thousands descended on the area around the London Stock Exchange yesterday in a bid to replicate the huge demonstrations taking place in New York.
As night fell protesters had pitched tents at the foot of the steps of St Paul's Cathedral after police cordoned off Paternoster Square, where the Stock Exchange is located.
Scotland Yard had said it would be "illegal and disrespectful" to camp in front of the cathedral, but a spokesman for the Metropolitan Police later said: "We are not going to move anyone at this time."
The force said it had made efforts to ensure yesterday's protest was largely peaceful.
Five arrests were made throughout the day - three for assault on police and two for public order offences.
A spokesman for the protesters said the demonstration was to "challenge the bankers and the financial institutions which recklessly gambled our economy".
"This occupation and 20 other occupations all around the UK have been directly inspired by what's happening all across America and especially Wall Street," he added.
Spyro Van Leemnen, a supporter of Occupy London Stock Exchange, was among those camping outside St Paul's.
The 27-year-old, originally from Greece, said: "There are about 100 tents here - in the churchyard, on the steps, and in between St Paul's and Paternoster Square.
"There are still a lot of police here but it's all very peaceful."
Mr Van Leemnen, who said he works in public relations, described the protest as the "initial stage of the movement to start a dialogue" and said it was about "democratising the financial system".
He added: "We're going to stay until the morning and the next day and the day after - as long as it takes until the Government hears our voice and says they are going to change things."
He foresaw no problems for when worshippers begin arriving in the morning, adding: "This is a peaceful movement. I'm sure the people who go to the cathedral won't be up for a fight."
A Metropolitan Police spokesman said the protest had been "largely calm and orderly", but urged protesters to leave the area around the cathedral.
However, Occupy London Stock Exchange supporter Anna Jones claimed "a disproportionate amount of force" was used by police against protesters outside St Paul's.
She said: "We have seen people, kettled, grabbed and thrown off the steps forcefully by the police. This was entirely unnecessary. None came here to have a fight with the police."
Earlier, police began removing protesters from the cathedral steps, leading to physical confrontations, and officers expressed concerns about the cathedral's pillars being damaged by people sitting on its steps.
A Met spokesman said a "containment" was carried out in the churchyard "prevent a breach of the peace".
Well-known activists including Julian Assange and Peter Tatchell were among the protesters in London yesterday.
Mr Assange, creator of the WikiLeaks website, addressed the crowds on the steps of St Paul's.
A spokeswoman for the protesters said he had been challenged by police for wearing a mask as he walked to the protest.
She said: "As I understand it, Julian initially refused to take the mask off. Police detained him for 15 minutes before letting him go.
"He then gave a speech in which he talked about WikiLeaks, police oppression and the current economic situation."
Activists carried banners with slogans such as "We are the 99%" and "Bankers got a bailout, we got sold out".
Among them was Lorena Fuentes, 27, a charity worker originally from Vancouver, Canada.
She said: "I'm here today because I can't see why you wouldn't be and I feel that this is one of the few moments in history where it's not a protest, it's an actual movement that's taken root.
"We're trying to challenge this myth that there are not enough resources to go around."
Protests also took place on the streets of Edinburgh and Dublin, which passed off peacefully.
More than 100 demonstrators turned out to protest in St Andrew Square, Edinburgh, while hundreds also took to the streets of Dublin.
In Italy however, police fired tear gas and water cannons as protesters turned the demonstration against corporate greed into a riot, smashing shop and bank windows, torching cars and hurling bottles.
Police in riot gear charged the protesters and fired water cannons at them.
Several police officers and protesters were injured, including one man trying to stop protesters from throwing bottles.
All services at St Paul's Cathedral, the first of which was at 8am, are set to go ahead as planned today, Sky News reported.
One clergyman told the news channel: "I don't have a problem with people being out here and expressing their right to protest."
Around 70 tents were set up yesterday evening and through the night in St Paul's Churchyard after attempts to occupy the London Stock Exchange in nearby Paternoster Square were blocked by police.
Ben Doran, 21, a music student from the Midlands who stayed at the makeshift campsite last night, witnessed the scene.
Mr Doran said a clergyman had come out on to the cathedral steps this morning and expressed his support for the protesters.
He said: "The reverend came out this morning and asked the police to leave the steps of the cathedral and said he didn't mind protesters being here, that he supported the democratic right to protest.
"He said there was no issue and that people were treating the site respectfully and he was happy for it to carry on.
"He was asked if the services would still be carrying on and he said yes, they would carry on as if there was no problem happening.
"The response from protesters was very positive, everybody likes to feel that the community around us are helping out."
One protester, a pensioner from London who gave her name as Ruth, said: "The vicar said he had no problem with us being here, he could see we weren't here against the church, we were here against the stock exchange.
"He said that the bad news was that the cathedral's bells are really loud, that our samba band was loud last night but we ain't seen nothing yet, and that it would wake us all up.
"We said that's absolutely fine with us and we're delighted to have his support."
Worshippers at the cathedral also expressed their support for the protesters.
Diane Richards, 36, a mental health support worker from south London who worships occasionally at St Paul's, said: "The general atmosphere within the church this morning has been quite supportive.
"The protesters have kept it well organised, they are trying to keep a very peaceful demonstration."
John Maguire and his wife Gail, from Haslemere, Surrey, attended the service to celebrate their twelfth wedding anniversary.
Mr Maguire, 51, a charity worker, said: "I think the protesters have got a valid point to make and obviously they want to make it in the most visible sense, so I'm pleased for them."