* Hedegaard says science shows oil sands more polluting
* Britain, others lend backing to Canada in fight against EU
* Environmentalists firmly back European Commission stance
By Johanna Somers
BRUSSELS, Oct 27 (Reuters) - The European Commission's plans to class fuel from oil sands, including Canada's, as highly polluting are based on science and it will proceed with talks with EU member states to implement the measure, its climate commissioner said on Thursday.
Canada, which has huge deposits of the unconventional crude oil, has hit back fiercely at a European Union proposal to label oil sands as carbon-intensive, in a ranking designed to help fuel suppliers choose the most environmentally friendly option.
Canada fears the ranking could damage the market for its oil. Natural Resources Minister Joe Oliver has said the Commission's proposal is based on politics, not science.
Climate Commissioner Connie Hedegaard denied that it is politically motiviated.
"We have the knowledge and the fact that oil sands are more CO2-polluting than other kinds of fuel," Hedegaard told a conference in Brussels.
"And therefore we say it should have a specific value. It's nothing targeted against this particular fuel. We are doing that with all our different biofuels. It's the same methodology that we are applying for different things in the same directive," she said.
"And now we are discussing this also with our member states, with the Commission, which has proposed this."
The 2008 fuel quality directive assigns greenhouse gas emissions values for a range of transport fuels, most of which were dealt with by the end of last year.
After earlier lobbying by Canada delayed the process, it was only provisionally approved earlier this month that oil sands would be included in the EU's fuel quality directive.
The news on Oct. 4 triggered another round of lobbying by Canada, which has won the support within the 27-member European Union from Britain and Eastern European states, EU sources said.
Environmental groups have strongly supported the Commission.
"Canada's plans for tar sands will put the world on track for 6 degrees of warming, way past the globally accepted limit of 2 degrees," said Franziska Achterberg of Greenpeace.
"Six degrees would be game over."
The proposed ranking assigns oil sands crude a default greenhouse gas value of 107 grams of carbon per megajoule, compared with 87.5 grams for conventional oil.
Two of the other unconventional fuel sources have higher values than oil sands. They are oil shale at 131.3, found in EU-member Estonia, and coal-to-liquid at 172.
The EU has a set of 2020 goals to make its energy mix more environmental, including cutting the amount of carbon it releases by 20 percent compared with 1990 levels.
As part of that target it has agreed to reduce the carbon intensity of its transport fuels by 6 percent. (Writing by Barbara Lewis; editing by Rex Merrifield and Anthony Barker)