A group of investors has filed a resolution demanding that BP does not invest in drilling in Canadian oil sands, which emits more CO2 than conventional drilling.

The Co-operative Asset Management, the Unison Staff Pension Scheme, a group of clients from Rathbone Greenbank and the COIF Charities Investment Fund are all signatories to the resolution which tells BP not to commit $10bn (£6.4bn) to its Sunrise oil sands development.

The resolution follows similar action taken by investors in Royal Dutch Shell last month.

Vast reserves of oil lie locked in the area but processing them is more expensive and environmentally damaging than conventional oil exploration.

“We believe that environmental costs may make an expensive business prohibitively so, without fundamentally addressing the issue of a large net rise in emissions,” said Niall O’Shea, head of responsible investing at the Co-operative Asset Management. “BP should reassure shareholders that what they’re embarking on is fully costed, prudent and can withstand a more carbon-constrained world.”

BP is likely to make a final investment decision on the project later this year.

Under previous chief executive Lord Browne of Madingley the firm had said it would not invest in oil sands but new BP chief executive Tony Hayward told the Guardian last week that he saw no problem with such investments.

“Canadian heavy oil is going to be a very important part of America’s energy, ” he said.

Hayward is likely to be confronted on the issue at BP’s annual general meeting on 15 April.