CALGARY -- A prominent Canadian businessman has taken out full-page newspaper ads to declare his opposition to Suncor Energy's proposed hostile takeover of Canadian Oil Sands.

The ads placed by Seymour Schulich say Suncor (TSX:SU) has a lot to gain from acquiring Canadian Oil Sands (TSX:COS) and he believes there's evidence that Suncor is willing to pay more than it has offered.

"The fact is Suncor needs Canadian Oil Sands more than we need them . . . I'm not selling at this price and you shouldn't either," the open letter concludes.

The ads are published in the Tuesday business sections of The Globe and Mail and the National Post newspapers and appear as the two Calgary-based oilsands companies woo shareholders ahead of a of a Friday deadline set by Suncor.

Suncor said Monday that it will move on to other opportunities if, by Friday evening, it does not receive "substantial support" for its $4.3-billion, all-stock offer. It has also scheduled a Tuesday morning briefing for investors.

Meanwhile, COS issued what it called a "declaration of independence," reiterating its view that shareholders are better off in the long run if the company continues on in its current form, despite continued weakness in crude prices.

Both companies are partners in the Syncrude oilsands mine north of Fort McMurray, Alta., -- COS with 37 per cent and Suncor with 12 per cent.

COS's main asset is its Syncrude stake, whereas Suncor (TSX:SU) is one of Canada's biggest energy names, with vast operations in the oilsands and a host of other refining and offshore holdings.

In an interview Monday, Suncor CEO Steve Williams said the prospects of a sweetened offer are "very low," noting ongoing operational glitches at Syncrude and a deterioration in crude prices since Suncor first took its offer to straight to shareholders in October -- from close to US$50 a barrel then to below US$40 a barrel now.

"If we were going to be making the bid today, it would not be at this level," Williams said.

Schulich, who describes himself in the ad as a chartered financial analyst specializing in oil and gas, has become a prominent name in Canada because his success as an investor.

Among the public institutions that bear his name is the Schulich School of Business at York University in Toronto, the Schulich School of Medicine and Dentistry at Western University in London, Ont., and the Schulich Heart Centre at Sunnybrook Hospital in Toronto.