EAGAN, Minn. (AP) _ A union representing 6,700 flight attendants at Northwest Airlines was ready to go on strike today after all-night negotiations reached an impasse, according to a union spokesman.

There were contradictory statements from union officials about whether a strike had actually been called, but airline spokesmen said there was no sign that a strike was in progress.

''We've been put on hold. We are ready for a strike. If this impasse isn't taken care of there will be a strike,'' said Teamsters Local 2747 spokesman Jeff Musto. He did not give any details on the impasse.

The international director of the Teamsters airline division, William Genoese, had earlier said workers were being told to walk out but refused to specify how broad the walkout might be.

''It might be one city, it might be two cities, it might be three cities,'' said Genoese when asked whether the strike was general or selective. Genoese, who had earlier said selective strikes were possible to disrupt the airline's services, refused to elaborate.

A spokesman for Northwest said today the airline was preparing to carry out its strike-management program, but hoped that talks would resume.

''There's nothing scheduled, but we're hoping to get them back to the bargaining session,'' airline spokesman Redmond Tyler said. Tyler said the talks were ''recessed'' and there had been no flight cancellations.

''We did everything we possibly could to avoid a strike,'' Genoese said during the morning. ''Apparently the company feels it wants to take a strike on. If we want to close down the airline, we can close it down. They've got their hands full.''

Teamsters spokeswoman Barbara Graham, at union temporary offices at hotel near Detroit Metropolitan Airport, said shortly after Genoese's announcement that she had received no notice of a strike, but that the union was standing by.

''We've got about 70 picketers hidden way at the airport,'' said Ken Daugherty, another union official in Detroit.

Spot checks by The Associated Press at other airports around the nation served by Northwest uncovered no picket or other strike activity, and airline operations were reported normal from Honolulu to Boston.

''We're proceeding to implement our contingency plan,'' vice president of law and labor relations Terry Erskine said at Northwest headquarters. About 2,000 managers trained as flight attendants have been posted throughout the Northwest system with 200 newly-hired replacement flight attendants also ready to move, he said.

Erskine said the airline was prepared to handle the strike. ''We've been through this fire drill before,'' he said.

Representatives for Northwest Airlines and the union had continued negotiations after a midnight EST deadline. In earlier statements, Genoese said selective strikes would be used to keep the airline off balance.

''When you have them off balance, they can't put out the fire there and the fire over here,'' Genoese said early this morning. ''That works to our advantage in the situation.''

Genoese said selective strikes would begin taking place at various locations throughout the Northwest system to - in his words - ''disrupt their service.''

''We have a right to do it,'' Genoese said.

Some 6,700 Northwest flight attendants are represented by Teamsters Local 2747.

Jim Halverson, a spokesman for the Northwest unit of the Air Line Pilots Association, said about 20 union officials meeting in Bloomington Friday night would debate whether to honor picket lines.

''We feel we can pull a strike off without (the pilots') support,'' Local 2747 spokesman Musto said. ''If we get it it will be like an ace in the hand.''

The machinists union representing Northwest mechanics gave its support to an attendants' strike, but union representatives did not say whether machinists would honor attendants' picket lines.

Northwest spokesman Redmond Tyler said the machinists are under a contract that forbids them to strike in sympathy with another union.

Wage scales, pensions and work rules are among the major issues in the dispute. Former Republic Airlines flight attendants have been working under their old contract since Northwest acquired Republic in 1986, and many former Republic employees are paid less than their Northwest counterparts.

The company, the nation's fifth-largest airline, is trying to bring the workers under one contract and offered to bring former Republic employees up to the salary levels of Northwest employees. But the union claimed the airline is compensating by reducing vacation pay and retirement benefits.