GM wants staff to give up expensive benefits such as health insurance and pensions but the United Auto Workers union wants job security assurances and for the carmaker to commit to maintaining production in the US.

Workers began forming pickets outside GM plants in the US as the deadline for a deal passed.

In a statement GM said it was “disappointed” in the UAW's decision to call a national strike but added it was “fully committed” to working with the union to address the contract problems. The carmaker did admit, however, that bargaining would involve “difficult issues that affect the job security of our US work force and the long-term viability of the company”. The UAW hopes the talks with GM will establish a blueprint for similar negotiations with Chrysler and Ford.

The timing of the UAW's strike is untimely for GM as a prolonged stoppage could jeopardise several of the manufacturer's promising new models. The strike does not affect GM workers outside of the US. It is the first time that UAW has held a nationwide strike during contract negotiations since 1976.