The Government warned climate change protesters at Heathrow last night to stay within the bounds of the law, as fears grew that militant elements would mount illegal protests.

Downing Street said that any disruption to the airport’s day-to-day activities would be “unacceptable”, as one spokeswoman for the “climate change camp” said that illegal protests could not be ruled out. “People do have a right to protest in this country,” a Downing Street spokesman said. “But the Government believes action that would disrupt the running of Heathrow would be unacceptable.”

Some 250 people had set up camp last night on private land by the airport. The demonstration is officially set to begin this morning, with 2,000 people expected to attend.

Leila Harris, one of the protesters, said that illegal protests could not be ruled out, but that safety of passengers would not be jeopardised. “It will be an action that is agreed upon by consensus of all those at the camp,” she said. “We have ruled out going on the runways or anywhere near the planes. That’s for our safety, the safety of passengers and for everyone else.” Campaigners said that the injunction won last week by BAA, the airport operator, had only served to highlight the demonstration, set to last for a week.

Up to 1,800 police officers from four forces have been drafted in for the demonstration and about 25 officers carried out a surprise inspection on the site, between the villages of Sipson and Harlington, yesterday morning, with campaigners claiming that friction was already starting to show.

Protesters said that police had initially refused to allow the site to connect to mains water supplies and had blocked food deliveries. Alex Harvey, a camp spokeswoman, said: “We had established good lines of communication over the last six weeks. It was really disappointing that the police withdrew from negotiations. This is no way to start, to withdraw communications late at night and to arrive unannounced first thing the next morning.”

Those dropping off deliveries at the site yesterday said that they had been delayed for hours without explanation and had produce damaged. One delivery driver, Mark, 38, from Nottingham, said: “We were stopped at the end of the lane leading to the camp for at least two hours and searched under the Terrorism Act quite vigorously without being given any particular reason. There’s been no animosity from our side, but we’ve not been shown any respect in return.”

Two arrests were made, one for an outstanding criminal warrant, the other for suspected deception. Camp organisers have since agreed to let four officers remain on site. Chief Superintendent Ian Thomas said: “It’s very peaceful so far but the main problem is that they have set up on land where the owner doesn’t want them.”

Protesters have been angered by police announcements that they would use anti-terror laws, including stop-and-search powers. Ms Harvey said: “It is absolutely diabolical to be using terrorism powers in this way. We are not terrorists.”

Simon Baugh, of BAA, said: “We are doing everything in our power to make sure the 1.5 million passengers due to pass through Heathrow this week are able to do so comfortably. Many are families who will have saved all year to afford their holiday.”

Explore UK News

• Crime News

• Education News

• Health News

• Scotland News

Times Recommends

• Charles blazes trail as sun king
• Thalidomiders win payout 50 years on
• Libel gag on talk of 'medical hurricane'