London, England (CNN) -- Protesters briefly disrupted a London oil conference Tuesday that BP boss Tony Hayward pulled out of a day earlier.
Just before the welcoming speech by BP Chief of Staff Steve Westwell, who was standing in for Hayward at the World National Oil Companies Congress, a woman got on stage and started shouting. Security quickly removed her.
The woman was Greenpeace campaigner Emma Gibson, who told the crowd that "because BP is incapable of telling you the truth, I'm going to tell you what you need to know."
Another Greenpeace campaigner, Katie Swan, got on stage with a banner reading "Go beyond petroleum," a take on BP's slogan.
"Ladies and gentlemen, we need to speed up progress and make a push to end the oil age," Gibson said on stage, according to Greenpeace.
"That means stopping the push for dangerous projects to pump out hard-to-reach oil like deepwater drilling and the tar sands of Canada," she said. "Deepwater drilling risks disasters like the Gulf spill while tar sands means clear-cutting forests and literally cooking the ground below to produce oil. Politicians must make moves to spark an electric car revolution so our cars can run on clean renewable energy."
Hayward decided not to attend the conference because of his "commitment to the Gulf of Mexico relief effort," a BP spokesman said Monday.
Westwell started his speech by apologizing on Hayward's behalf for not being at the conference.
"He and I hope you will understand that his schedule is under incredible pressure as a result of current events," Westwell said.
Westwell said the past few weeks have been "extremely difficult for BP" following the accident on the Deepwater Horizon drilling rig in the Gulf of Mexico on April 20 that has sent oil spewing into the ocean.
"Eleven people died in the explosion and subsequent fire," Westwell said. "And the spill has had a very serious environmental impact. It has been hugely shocking for us, for America, and for the rest of the world.
"Everyone at BP is devastated, and we deeply regret what's happened. Our hearts go out to those who have lost loved ones. And we are profoundly aware of our responsibilities to those people whose livelihoods and neighborhoods have suffered."
He said BP is doing "everything in our power to put the damage right" and to learn lessons to prevent such catastrophes in the future.
"I'd also like to make it clear this is not simply about fulfilling our legal obligations -- we feel a huge moral responsibility," he said. "All of us at BP will work tirelessly to clean up this spill, repair the damage, and restore the Gulf Coast communities."
CNN's Ayesha Durgahee contributed to this report.