Canadian Oil Sands Ltd. continued to urge its shareholders to reject a bid from rival Suncor Energy, saying the offer would sell itself if it was worthwhile.

Suncor last month said its unsolicited $3.2 billion takeover bid for its rival was a "financially compelling" offer. Last week, Suncor called on the Alberta Securities Commission to consider a shareholder rights plan adopted by Canadian Oil Sands, which is designed to prevent the takeover.

Suncor, in a letter to rival shareholders, said a "do-nothing" stance from Canadian Oil Sands is a risky position given the continued weakness in the energy sector. In a new filing, Suncor said it updated information on the bid to reflect further evidence of the downturn in third quarter financial results.

Suncor is a minority stakeholder in the Syncrude oil venture in Alberta. Canadian Oil Sands holds a 37 percent stake in the project. Suncor's letter warned rival shareholders of the "risks they face if they reject the offer, given the new business reality for oil prices and [the company's] total reliance on the performance of the Syncrude oil sands facility, a single asset over which Canadian Oil Sands has little control."

Donald Lowry, board chairman at Canadian Oil Sands, said the latest move by Suncor represents a scare tactic meant to play on shareholder emotions.

"While Suncor uses fear and intimidation to pressure our shareholders, [the board] is working for shareholders by giving them more time through the shareholder rights plan and conducting a thorough evaluation of alternatives to surface better value," he said in a statement. "Those higher-value alternatives range from a superior offer to remaining an independent company."

Canadian Oil sands said that, if it represented a good value, the unsolicited bid "would sell itself."