'The biggest environmental crime in history'

BP, the British oil giant that pledged to move "Beyond Petroleum" by finding cleaner ways to produce fossil fuels, is being accused of abandoning its "green sheen" by investing nearly £1.5bn to extract oil from the Canadian wilderness using methods which environmentalists say are part of the "biggest global warming crime" in history.

The multinational oil and gas producer, which last year made a profit of £11bn, is facing a head-on confrontation with the green lobby in the pristine forests of North America after Greenpeace pledged a direct action campaign against BP following its decision to reverse a long-standing policy and invest heavily in extracting so-called "oil sands" that lie beneath the Canadian province of Alberta and form the world's second-largest proven oil reserves after Saudi Arabia.

Producing crude oil from the tar sands – a heavy mixture of bitumen, water, sand and clay – found beneath more than 54,000 square miles of prime forest in northern Alberta – an area the size of England and Wales combined – generates up to four times more carbon dioxide, the principal global warming gas, than conventional drilling. The booming oil sands industry will produce 100 million tonnes of CO2 (equivalent to a fifth of the UK's entire annual emissions) a year by 2012, ensuring that Canada will miss its emission targets under the Kyoto treaty, according to environmentalist activists.