UK Secretly Helping Canada Push its Tar Sands Project and Escape Dirty Fuel Designation in Europe

The UK government has been giving secret support at the very highest levels to Canada's campaign against European penalties on its highly polluting tar sands fuel, the Guardian can reveal.

At the same time, the UK government was being lobbied by Shell and BP, which both have major tar sands projects in Alberta, and opened a new consulate in the province to "support British commercial interests".

At least 15 high-level meetings and frequent communications have taken place since September, with David Cameron discussing the issue with his counterpart Stephen Harper during his visit to Canada, and stating privately that the UK wanted "to work with Canada on finding a way forward", according to documents released under freedom of information laws.

Charles Hendry, the energy minister, later told the Canadian high commissioner: "We would value continued discussion with you on how we can progress discussions in Brussels," with Hendry's official asking the Canadians if they had "any suggestions as to what we might do, given the politics in Brussels".

Canada's vast tar sands – also known as oil sands – are the second largest reserve of carbon in the world after Saudi Arabia, although the energy needed to extract oil from the ground means the process results in far more greenhouse gas emissions than conventional oil drilling, as well as causing the destruction of forests and air and water pollution.

Nasa scientist James Hansen says if the oil sands were exploited as projected it would be "game over for the climate".

The European proposal is to designate transport fuel from tar sands as resulting in 22% more greenhouse gas emissions than that from conventional fuels. This would make suppliers, who have to reduce the emissions from their fuels by 10% by 2020, very reluctant to include it in their fuel mix. It would also set an unwelcome precedent for Canada by officially labelling fuel from tar sands as dirtier.

The UK and Canada's shared opposition to the European plan puts the UK in a minority among EU countries and will be deeply embarrassing as a new round of global negotiations on tackling climate change begins in Durban, South Africa on Monday. Chris Huhne, the energy and climate change secretary, claimed on Thursday that the UK was showing "leadership" in the UN negotiations, while Canada's prime minister has blocked climate laws. The revelations are also the latest blow toCameron's claim to be the "greenest government ever".

The vote to approve the European fuel quality regulations takes place on Friday. In advance of that, William Hague, the foreign secretary, has also given support to Canada, sending an "immediate action" cable in September to the UK's embassies there asking "to communicate our position and seek Canadian views on what might be acceptable".

However, the Department for Transport, in which the Liberal Democrat minister Norman Baker has responsibility for tar sands issues, has released only two presentations made to it by Shell, both heavily redacted. The DfT rejected requests to release at least six other relevant documents on the grounds of commercial confidentiality and adverse effect on international relations, as did the Department for Business, Innovation and Skills (BIS), where Shell also met ministers.

BP has lobbied ministers, too. Its vice president in Europe, Peter Mather, has been, in his own words, "bending the ear" of Baker. Mather also sent a letter in which he wrote: "The regulatory burden would be considerable at a time when the industry is already creaking under the weight of a heavy regulatory regime."