Anti-capitalist protesters who have been camped outside St Paul's Cathedral for a month were today warned to quit their tents or face High Court action.
The City of London Corporation served a legal eviction notice on the activists which gives them until 6pm tomorrow to leave.
But demonstrators, who tore down the notices as soon as they were posted, vowed they would stay and said they were prepared to fight a potentially lengthy legal battle.
The corporation, the local authority which runs the Square Mile, has expressed concern over "worrying trends" at the camp, including late-night drinking, and said companies near the cathedral had complained about losing business.
Some of the tents are pitched on the footpath next to the shops surrounding the cathedral with the remainder in the churchyard itself.
A spokeswoman for the cathedral - which has ditched its own proposed legal action - said that it was looking for a "peaceful resolution" and said it had faced "challenges" since the camp was pitched a month ago.
The notice said: "If any tents and other structures remain after 6pm on Thursday 17 November 2011, proceedings for possession and injunctions will be issued in the High Court of Justice without further notice.
"If granted, this would mean that you would be ordered by the High Court to remove the tents and any failure to do so could be a contempt of court."
The corporation decided to resume legal action after two weeks of talks with protesters.
Stuart Fraser, policy chairman of the corporation, said previously: "We paused legal action for two weeks for talks with those in the camp on how to shrink the extent of the tents and to set a departure date - but got nowhere.
"So, sadly, now they've rejected a reasonable offer to let them stay until the new year, it's got to be the courts.
"We'd still like to sort this without court action but from now on we will have to have any talks in parallel with court action, not instead."
Naomi Colvin, an Occupy London spokeswoman, said: "It is not something we need to be remotely worried about - we've been prepared for it for months.
"If they want to get an order in the High Court, it could take months. We will contest it.
"We will be speaking to our legal team and we will be fighting it."
She questioned the corporation's motives for asking the protesters to leave, adding: "The area by the side of St Paul's Churchyard is not obviously in anyone's way - people move freely up and down it every day.
"They say it is a highway but there haven't been horses and carts here for hundreds of years.
"People are so serious about this crisis that they are willing to leave their homes and camp out during the English winter."
A sign on one of the tents in the camp made its owner's views clear: "Hell, no - we won't go!"
Tammy Lawrence, a 33-year-old demonstrator, said that she was staying put.
"I get freezing cold at night but I believe in what we're doing and I'm happy to sacrifice something for it.
"If you're so angry we're blocking a public highway can you tell us why you've allowed us to be here for a month?
"They offered to let us stay for two months so they're happy for us to break highway laws for two months but not for longer."
She said she would fight the notice: "All we're going to do if the police come in is sit down."
A St Paul's spokeswoman said: "We are committed to maintaining St Paul's as a sacred space in the heart of London and we are enormously grateful to all cathedral staff for meeting the challenges of recent weeks.
"We recognise the local authority's statutory right to proceed with the action it has today.
"We have always desired a peaceful resolution and the Canons will continue to hold regular meetings with representatives of the protesters.
"We remain committed to continuing and developing the agenda on some of the important issues raised by the protest."
Two senior clergy members quit when the cathedral was exploring the possibility of legal action.
Adam Chapman, head of public law at law firm Kingsley Napley, said: "For the city to get an injunction to evict them, they're going to have to show that is a proportionate step, taking into account on the one hand other people's right to free movement and on the other hand the right to freedom of expression and assembly.
"The court will have to weigh up the degree of interference as against the importance of the right to demonstrate.
"I assume the corporation won't try to remove protest altogether but simply sleeping out overnight and the court will consider how integral that is to freedom of expression."
He said that when a court moved to ban protesters camping outside Parliament earlier this year, it took into account that they could remain during the day.
The proceedings at Parliament Square took a year and Mr Chapman expects any eviction action at St Paul's will also take several months.
"I'd say the corporation will succeed in the end but it will take some time.
"We're talking months - possibly six months but certainly beyond Christmas and into the New Year."
In the early hours of yesterday morning, police wearing riot gear moved in to clear Zuccotti Park in New York City's financial district, where protesters from the Occupy Wall Street movement have been camped since September.