Environmentalists and police kept a wary truce Monday at the start of a weeklong "climate camp" to protest a proposed new runway at Heathrow Airport and highlight air travel's contribution to climate change.
About 150 protesters erected tents in a field north of Heathrow's perimeter fence, along the route of a proposed third runway. Airport operator BAA PLC won an injunction last week barring protest group Plane Stupid from the airport, but other groups were allowed to demonstrate provided they do not disrupt the airport's operations.
Prime Minister Gordon Brown's office warned the demonstrators not to interfere with the running of the airport.
"People do have a right to protest in this country, but the government believes that action that would disrupt the running of Heathrow would be unacceptable," a Downing Street spokeswoman said on condition of anonymity in line with government policy.
Members of Plane Stupid, the group banned from the airport, on Monday staged a sit-in on a barge carrying the newly built wing of an Airbus A380 from a factory in north Wales.
"Extraordinary times call for an extraordinary response, and that's why we've set up a climate camp under the wing of an Airbus super-jumbo," said protester Leo Murray.
North Wales Police said six protesters were removed from the barge by Airbus security guards. No one was arrested.
Organizers say as many as 1,500 people are expected to attend the Heathrow camp, which is due to culminate in a day of unspecified "direct action" on Sunday.
One of the protesters, Gary Dwyer, 34, said he expected the event to be peaceful.
"There will be the day of direct action, but we've said there will be no attempt to storm runways or anything like that. Public safety is paramount," he said.
Up to 1,800 police officers will be on duty during the protest, which officially starts on Tuesday. Some civil rights activists have voiced concerns at police tactics after officers made it clear they would deal "robustly" with any problems.
The Metropolitan Police said Monday that officers were "carrying out routine patrols throughout the camp, to ensure that offenses are not committed."
Protest organizers said their aim was not to disrupt people's travel plans, but to start a debate about airport-linked environment damage.
"Our plan has always been that people who come to the camp will decide themselves what kind of action they want to take, but we have been very clear that we will not be going onto Heathrow's runways," said Gemma Davis, a spokeswoman for the Camp for Climate Change.
Mark Bullock, managing director of BAA Heathrow, said the airport operator would take all the necessary steps to protect staff and travelers during one of its busiest weeks of the year.
"With the current terrorism threat, keeping Heathrow safe and secure is a very serious business," Bullock said. "Any action taken by the protesters that distracts us or the police from this task is irresponsible and unlawful."
A fifth terminal is scheduled to open at the airport in March 2008, and the government has proposed a new runway there for about 2020.