LONDON (AP) — Greenpeace activists scaled BP's London headquarters yesterday to hang a flag accusing the oil company of polluting the environment.

The flag was a parody of BP PLC's logo, which showed oil dripping from the company's yellow and green sunburst and had the words "British polluters" underneath. The group said the action was prompted by the Gulf of Mexico oil spill as well as a controversial project in Canada.

"It takes some cheek to go and use a sunflower logo when your business is dirty oil," Greenpeace activist Ben Stewart said from a balcony above the headquarters' front door in a telephone interview.

BP spokesman Robert Wine called the action "a very calm and genteel protest", and said no employees had been prevented from getting to work.

London police said officers were at the protest, but that there had been no arrests.

Stewart said protesters were expecting BP chief executive Tony Hayward at the company's central London offices for a meeting. But Wine said Hayward was in Houston, and was not expected back in London.

The Gulf of Mexico oil spill began April 20, after an explosion on the drilling rig Deepwater Horizon, which was owned by Transocean Ltd. and leased by BP. The explosion killed 11 workers on the rig. Since then, oil has been pouring into the gulf from a blown-out undersea well at a rate of at least 210,000 gallons per day.