The City of London Corporation has attached eviction notices to tents belonging to Occupy London protesters outside St Paul's Cathedral.
The notices warn the anti-capitalist protesters that proceedings will be issued in the High Court if they are not removed by 6pm on Thursday.
According to the Corporation it made the decision to issue an eviction notice after discussions with the protesters "got nowhere".
Stuart Fraser, policy chairman of the City of London Corporation, said he had reports of "worrying" activities at the camp.
‘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," he said.
"So, sadly, now they have 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.
"We are getting reports about vulnerable people, cases of late-night drinking and other worrying trends, so it’s time to act. It will clearly take time but we are determined to see this through.
"Lawful protesters who stand or walk are a regular part of London. But tents, equipment and now, increasingly, quite a lot of mess, is not what a highway is for and others are losing out."