MONTREUX, Switzerland (AP) _ The World Luge Championships, scheduled for this weekend, have been postponed until Feb. 20-21 due to lack of snow, organizers said Friday.

Twelve national teams are expected for the event, to be held on a 1,087- meter natural course, said Jacques Serex, secretary of the organizing committee.

Scheduled participants include U.S., Soviet and East and West European racers. Canada also was expected, but bowed out due to a schedule conflict, Serex said.

The championships will draw other racers than the luge competition at the Winter Olympics, set for Feb. 14-19, because the Olympic discipline is run on an artificial course, he said.

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CANTON, Ohio (AP) - James Machnik, commissioner of the American Indoor Soccer Association, has ruled that the Canton Invaders must forfeit last Saturday's game against Memphis, which was halted at halftime after the referees were allegedly attacked by the team's owners.

Invaders owner Steve Paxos said the team would be fined a ''substantial amount'' by the league for the incident.

Paxos had threatened to boycott this weekend's games at Memphis because of what he felt was unfair treatment at a fact-finding meeting Wednesday. But he relented Thursday and sent his team to Memphis.

Paxos and his brother, Nick, owners of the Invaders were accused of assaulting the referees at last Saturday's Memphis-Canton game at the Canton Civic Center. The referees called the game at halftime with Memphis leading 4-3.

The game will be recorded as a 1-0 Memphis victory, ending the Invaders' chances of winning the AISA championship.

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NEW YORK (AP) - Four-time winner and defending champion Sammy Koskei of Kenya and American 800-meter record holder Johnny Gray will head the field for the 1,000 meters in the Millrose Games Feb. 5 at Madison Square Garden, meet director Howard Schmertz announced Friday.

Also in the 1,000 will be Stanley Redwine, a Millrose winner at 600 yards in 1983 and 1984 and in the 800 last year.

Schmertz also announced the field for the 600-yard race. It includes defending champion Ian Morris of Trinidad, 1986 winner Elvis Forde of Barbados, 1985 500-meter champion Ray Armstead, and Chip Jenkins, son of 1956 Olympic 400-meter gold medalist Charles Jenkins.

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PARIS (AP) - Kelvin Seabrooks of Charlotte, N.C., will defend his International Boxing Federation bantamweight title Feb. 6 against Fernando Beltran of Mexico at Pierre de Coubertin Stadium, organizers announced Friday.

Seabrooks originally was scheduled to meet Louis Gomis on that date at La Seyne sur Mer on the French Riviera, but an eye injury forced Gomis to retire from boxing.