General Motors workers will go on strike at a Portuguese assembly plant on Tuesday and stage protests elsewhere after talks to save the Azambuja factory failed, the carmaker's European works council told Reuters on Monday.

Accusing the company's management of intending to close down plants in western Europe as it shifts production eastward, the employee forum also said GM planned to buy a plant in Poland where it will make so-called Gamma platform cars in future.

Last month Portugese economy minister Manuel Pinho told Reuters his government was committed to creating the necessary conditions for General Motors to keep the light commercial vehicle plant open.

Pinho reportedly said the challenge would be to boost competitiveness at the factory, where GM had said a few days earlierit was seeking to cut costs. GM had not ruled out closing the factory, which employs 1,100 workers.

Reuters noted at the time that GM had said costs at the Azambuja plant were EUR500 ($US643) more per vehicle than at other possible locations.