Greenpeace protesters 'greenwash' the words 'tar sands' outside BP's Calgary offices Thursday to condemn the firm's proposed oilsands project near Fort McMurray. (CBC)

About a dozen Greenpeace activists staged a protest outside BP's Calgary headquarters Thursday to condemn the U.K. petroleum giant's proposed oilsands development in northern Alberta.

"We're here today to expose BP's attempt at greenwashing the tarsands," said Melina Laboucan-Massimo, a spokeswoman for Greenpeace Canada.

BP has moved to rebrand itself as an environmentally friendly energy firm in recent years, adopting a new logo with a flowerlike sunburst design and the slogan "Beyond Petroleum."

But the company's foray into Alberta's carbon-intensive oilsands sector has drawn charges of hypocrisy from environmentalists.

"BP is no longer able to claim that it is beyond petroleum. Because of BP's involvement in the tarsands, BP has now broken its promise," Laboucan-Massimo said.

Protesters dressed in business suits and top hats assembled giant letters spelling the words "tar sands" and used rollers to paint them green.

But the spectacle on Fourth Avenue and Second Street S.W. — timed to coincide with BP's annual general meeting in London — drew more hecklers than supporters, according to the CBC's John Spittal.

The Greenpeace protest against U.K.-based oil giant BP drew hecklers but few supporters in Calgary. (CBC)

"The yellow poles that they are using are made of plastic. The paint is petroleum based," said bystander John MacKenzie. "So, I would suggest they do some research on their protest prior to them protesting."

Several police officers were on hand and security staff restricted access to the office tower to tenants and their guests during the protest.

BP is partnering with Calgary-based Husky Energy in the Sunrise project, a massive oilsands development northeast of Fort McMurray.

At BP's worldwide headquarters in London, a shareholder rights group used the firm's AGM to lobby the energy giant to release more details about the plan.

The group proposed a resolution — which was easily defeated — calling on the company to review its calculations on future oil demand, the costs of carbon capture and storage technology as well as the extent of the project's environmental impact.

The fact that BP — so far not a major oilsands player — is even considering the Sunrise project is proof the firm is not serious about its stated commitment to moving beyond petroleum in favour of cleaner energy, according to Laboucan-Massimo.

"There's a whole host of issues with BP's involvement in the tarsands. It's actually more water intensive, more energy intensive than open pit mining is. It's dirty oil at the end of the day."

With files from the CBC's John Spittal