The United Auto Workers is suing General Motors Co. for the automaker's use of temporary workers at Fort Wayne Assembly in Indiana, a move the union says is a breach of the parties' labor contract.

The UAW is arguing that some 1,000 laid off GM-UAW workers — including 690 "seniority employees" laid off from Lordstown Assembly in Ohio who have requested transfers to Fort Wayne — are entitled to positions in Fort Wayne that are currently being filled by temporary workers.

The lawsuit, filed Thursday in a U.S. district court in Ohio, alleges GM is "circumventing the parties' agreement on employee placement by employing temporary employees at Fort Wayne Assembly rather than transferring laid-off seniority employees under the provision of Appendix A — Memorandum of Understanding Employee Placement."

The UAW is asking the court to order GM to stop using temporary employees in Fort Wayne, where the automaker's heavy-duty pickup trucks are built, and transfer the senior employees to the facility. The union is also asking that affected senior employees be compensated for all losses resulting from GM's alleged breach of contract.

“UAW members negotiated a binding agreement and we expect General Motors to follow the contract they agreed to and GM members ratified,” said Terry Dittes, UAW vice president and director of the GM department, in a statement.

GM says it started the process last year to bring 50 Lorsdtown employees to Fort Wayne to fill jobs previously held by temporary employees, 35 of which will be placed by the end of January.

"We have ongoing discussions with the UAW regarding our staffing needs in Fort Wayne, but have no further comments on the lawsuit," GM said in an emailed statement.

The portion of the GM-UAW contract cited in the union's lawsuit states that laid-off and active "seniority employees" — defined as production employees with two or more years of seniority — will be given the opportunity to relocate to other GM facilities, particularly when the home facility of the employee has been idled or closed. The Memorandum of Understanding Employee Placement also states that laid-off senior employees can be hired to fill temporary job openings.

The UAW's lawsuit comes as unions in the U.S. and Canada have intensified their public campaign to keep open five GM plants in North America.

The UAW has already challenged GM's decision to leave four U.S. plants "unallocated" later this year, accusing the Detroit automaker of deliberately avoiding the words "idle" or "close." The "Plant Closing and Sale Moratorium" in the 2015 GM-UAW contract forbids GM from idling or closing a plant outside of collective bargaining, with a caveat for extreme market conditions or an "act of God."

nnaughton@detroitnews.com

Twitter: @NoraNaughton