Prime Minister Stephen Harper is warning Canadians that a proposed buyout of Calgary based Nexen is far from a done deal.

Harper says the bid from the China National Offshore Oil Company will be carefully scrutinized and evaluated based on whether it's of net benefit to Canada. He says nothing has been decided as of yet and nobody should prejudge the outcome of the Competition Bureau's review.

The friendly bid promises to maintain Calgary's base and keep all of its current employed and management.  If approved, it would be China's largest ever overseas acquisition.