Alberta's Liberals are raising questions about whether a giant oilsands tailings pond in northern Alberta is leaking contaminated water into the nearby Athabasca River.

The opposition is pointing at a report prepared for Suncor last November that estimates that more than five million litres of toxic liquid per day is leaking from one of the company's tailings ponds.

The report prepared by IPEC Consultants says that most seepage is `collected and returned to the pond.'

But Liberal environment critic David Swann suspects that a large amount of the seepage from the Tar Island Dyke eventually ends up in the river.

Environment Minister Rob Renner says the tailings pond is nearly 60 years old, but the seepage collection system is working and there's no evidence of river contamination.

When asked by Swann if he would drink the river water, Premier Ed Stelmach accused the opposition of trying to grab headlines with unfounded allegations.