Ralston Purina Co. agreed today to sell the St. Louis Blues to a group of Canadian businessmen, who would attempt to move the National Hockey League team to Saskatchewan, a spokesman said.

The company announced that its board of directors authorized the sale to Coliseum Holdings, Ltd., of Saskatoon, Saskatchewan, despite a last-ditch effort by a group of local businessmen.

The Canadians are believed to have offered $13 million for the club, while the local group, headed by St. Louis Mayor Vincent Schoemehl, could come up with only about $8 million.

NHL bylaws specify that unanimous consent of its board of governors is required for sale of a team. However, the rules may be adjusted for specific cases and that could be the case for the Blues, who became a member of the league as an expansion franchise in 1967.

Saskatoon businessman Bill Hunter, one of the founders of the now defunct World Hockey Association, said only a formal signing of documents is left to make final the sale that would make Saskatoon, with a population of 163,000, the smallest NHL city and the eighth Canadian NHL franchise.

Hunter said he expected the league would be asked to convene a special board of governors meeting in a few days. However, the meeting may not go as smoothly as Hunter might expect.

NHL President John Ziegler has repeatedly said he does not favor moving the team out of St. Louis and would do everything possible to keep it there.

In Toronto, Maple Leafs owner Harold Ballard was angered by the sale.

"The people who are buying it are a little dumb," he said. "It has to be unanimous but, if not, I know 80 to 85 percent of the 21 teams will not vote to move that franchise."

Edmonton Oilers owner Peter Pocklington said he expected the sale to meet some opposition but "Saskatoon has my vote . . . "