MINNEAPOLIS - The union representing striking mechanics at Northwest Airlines Corp. has discontinued negotiations, a Northwest spokesman said Sunday. It wasn't immediately clear whether the union might return to bargaining ahead of a Tuesday deadline for replacement mechanics to be hired permanently.

Kurt Ebenhoch said the national mediation board informed Northwest of the decision by the Aircraft Mechanics Fraternal Association on Sunday.

"We remain available and willing to return to the table," Ebenhoch said. He declined to comment further.

When reached by phone, AMFA negotiations spokesman Jeff Mathews said, "There's no negotiations scheduled at this time," and refused to elaborate.

Fifteen hours of talks between Northwest and its striking mechanics ended early Sunday without an agreement.

The carrier has kept flying through the strike that began on Aug. 20. The negotiations had restarted on Thursday after the airline threatened to begin hiring permanent replacement workers on Tuesday if no deal is reached.

The union has said Northwest wants to keep only 1,080 mechanics' jobs and eliminate the aircraft cleaner and custodian positions represented by the union. That represents about 3,350 layoffs, up from the 2,000 Northwest sought before the strike. About 200 of the remaining mechanics' jobs would be in Duluth, with the rest split between Minneapolis and Detroit.

Northwest's proposal would save it $203 million a year, up from the $176 million it sought before the strike began Aug. 20.

"Their first proposal was bad; their second was horrendous," Steve MacFarlane, AMFA's assistant national director, said on Sunday.

Mechanics made their own proposal on Saturday, but they didn't release details.

Northwest is seeking $1.1 billion in annual labor cost savings from all its workers, and it has said rising fuel prices mean it will probably raise that target. It is in talks with all of its workers.

Northwest has said time is running out for it to avoid bankruptcy. Oct. 16 is the last day before a new, more restrictive bankruptcy law takes effect, and CEO Doug Steenland has acknowledged that the law change is one factor in the company's bankruptcy considerations.