GM said late in the day it filed a grievance Tuesday with the Union's international leaders, seeking unspecified damages and requesting a response within 48 hours.

The automaker, which has now idled 146,400 non-striking workers in North America because of parts shortages, also said it will protest paying state unemployment benefits in all of the states where workers have been forced off the job because of the two parts plant strikes in Flint, Mich.

"General Motors has taken additional steps to further protect its financial position and expedite an end to this costly and senseless strike," Gerald Knechtel, vice president of North American Personnel, said.

About 3,400 workers struck the metal stamping plant on June 5, and 5,8004 more workers struck a second GM parts plant in Flint on June 11. Shortagesfrom the plants have halted or curtailed output at 26 of 29 North American assembly plants.

The strikes are estimated to be costing GM upwards of $75million a day in lost profits. By the Fourth of July weekend, the total cost of the strikes could hit $1 billion.

Union leaders at the UAW 32nd Constitutional Convention in Las Vegas, Nev., quickly shot back at GM's latest actions.

"It says to me that they're still trying to find ways to twist the issues, to avoid sitting down with the local union and the international union and finding a way to resolve the dispute," said Richard Shoemaker, the UAW vice president in charge of the GM department. "That's the only way they're going to settle this."

UAW president Stephen Yogic added: "I don't even want to talk about it. I don't want to ruin my day." In its statement, GM said the strikeable issues identified by the union are "contrived," adding "the real issues that led to these costly disputes are ones that the Union has agreed to be nonstrikeable."

The UAWlegally has the right to strike only on issues related to worker health and safety and over production standards. Although the major issues at the Flint Metal Centre are job security and commitments for future investment, the union has said its grievances affect safety and production standards.

At Delphi East, the UAW has said the strike is over health, safety, subcontracting and production standards. But union leaders are known to be angry over company plans to send out work that would cost 2,500 jobs. Harley Shaiken, a University of California-Berkeley labour relations professor who is attending the convention, said GM has little chance of winning a court injunction to stop the strikes, but said it shows a settlement is not close at hand.