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COPS have made six arrests during today's (Sunday's) Climate Camp protests.
Gareth Green, spokesman for the Metropolitan Police said: "In total there have been six arrests made in the Heathrow Airport area during the day.
"The arrests have been made for a variety of public order offences and drugs offences."
Earlier, between 1,000 and 1,400 Climate Camp protesters marched along the route of the proposed third runway.
Now around 300 of those are camped outside BAA's corporate headquarters in Mondial Way, off Bath Road, near Heathrow Airport.
Police in full riot gear have surrounded the building. Officers have also isolated a group of about 50 activists, in Mondial Way, after missiles were thrown during an earlier clash with police.
But despite a number of small scuffles breaking out, the protests have been largely peaceful. This has led some campaigners to accuse the police of mounting an over zealous operation.
Charles Cooley, 43, from Hayes was not staying at Climate Camp, but joined the march for the day.
He said: "It's very bad. This is a peaceful protest and they're being extremely heavy handed."
Shona Gazidis, 23, travelled from Birmingham to join the march. She said: "The police presence is a bit of a waste of time.
"It's been very much an organised protest and it's been quite calm. It's all a bit unnecessary."
Mr Green said police would only have arrested people who were breaking the law and the police presence was necessary to ensure the public's right to protest peacefully.
He said he could not confirm whether police would clear protesters from BAA headquarters.
Activists are expected to remain outside the building until 12pm on Monday.
BAA spokesman Ben Morton said the company was pleased there had been little disruption so far.
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