BP has been given permission to restart deep drilling in the Gulf of Mexico, one year after the Deepwater Horizon explosion killed 11 workers and caused the worst oil spill in history. The group plants to drill 10 existing wells from this summer, following a deal with US regulators to continue work halted by a moratorium imposed after 200 million gallons of oil were leaked into the Gulf.

The plans, which have angered environmentalists, are a coup for Bob Dudley, BP's new American chief executive, who replaced Tony Hayward after he was criticised for his handling of the crisis.

Meanwhile Transocean, the world's largest offshore rig company – which leased the Deepwater Horizon rig to BP – has awarded "safety" bonuses to senior executives for achieving "the best year in safety performance in our company's history", in spite of the disaster. Nine of the workers killed were Transocean employees.

"Notwithstanding the tragic loss of life in the Gulf of Mexico, we achieved an exemplary statistical safety record as measured by our total recordable incident rate and total potential severity rate," Transocean said.

"As measured by these standards, we recorded the best year in safety performance in our company's history, which is a reflection on our commitment to achieving an incident-free environment, all the time, everywhere."