More than 20 arrests have been made after anti-capitalist protesters attempted to occupy a building near Piccadilly Circus in central London.
About 60 Occupy London Stock Exchange (OLSX) protesters tried to get into Panton House on Panton Street.
Riot police entered and cleared the building making 24 arrests.
An OLSX spokesman said protesters were targeting Mick Davis, chief executive of mining company Xstrata, which has offices in the building.
Occupy London supporter Karen Lincoln said: "Mick Davis is a prime example of the greedy 1% lining their own pockets while denying workers pensions."
An Xstrata spokeswoman said: "All executive pay is approved by the company's shareholders and is linked to company and individual performance.
"Last year Xstrata delivered its second best financial performance since inception, with an 86% increase in profits, record cost savings, improved safety performance and total shareholder returns substantially greater than the FTSE 100 average."
Arrests were made for a variety of offences including burglary, aggravated trespass, criminal damage and assault on a police officer.
Five people have been released on bail and 19 remain in custody.
Police said the incident was isolated and not related to the march and rally in support of public sector workers which passed off peacefully.
'Shame on you'
The protesters gathered at Piccadilly Circus just before 15:30 GMT.
Most were held at bay by police but a few got inside and went on to the roof, where officers moved in to clear them.
Police vans were seen pulling up at the scene in Haymarket while protesters were contained in the area outside Panton House.
Police sealed off the area around Panton Street and marched through the 200 to 300 protesters, to shouts of "shame on you".
Police told the protesters by megaphone announcement from a van: "You are being contained because we fear an imminent breach of the peace will occur.
"You will be released as soon as possible."
A Scotland Yard spokesman said: "At approximately 15:50 GMT a containment was put in place outside Panton House, Haymarket, to prevent disorder by a group of protesters outside the building.
"Some protesters have entered the building and officers are in the process of making arrests for aggravated trespass."
Sarah Porter, head of the Heart of London Business Alliance which represents 500 businesses in the area, said: "Many of our businesses have been directly affected by the protests and we have advised them to remain vigilant."
Since the Occupy movement protests began in New York, in September, a protest camp has been set up by the group in the City of London.
The City of London Corporation is currently taking legal action to move the protesters from outside St Paul's Cathedral.
Members of the group have also taken over an empty office block in Hackney, east London, belonging to Swiss Bank USB.
The group say they are protesting against capitalist greed.