CALGARY - An environmental justice group says it has filed an application asking energy regulators in Alberta to revoke its approval of an oilsands company's plans to clean up toxic waste ponds.

Barry Robinson, a lawyer with Ecojustice, says Syncrude's tailings management plans for its Mildred Lake and Aurora North projects don't meet rules laid out in 2009 by the Energy Resources Conservation Board.

He says the board calls for a 50 per cent reduction of fine soil particles in tailings by 2013.

Robinson says the Mildred Lake project would only see a 35 per cent reduction by that deadline and the Aurora North plant predicts an 11 per cent reduction.

Board spokesman Davis Sheremata says Syncrude officials have told them they need until 2014 to meet the rules because the effort will cost hundreds of millions of dollars and require building two tailings facilities.

He says they granted an extension to Syncrude because the board felt the company was doing everything possible to comply with the board's regulations.