German industrial union IG Metall reportedly said on Tuesday it would continue its campaign of limited stoppages with demonstrations planned at centres including Ford Europe's plant in Cologne and Porsche in Stuttgart.

Thousands of workers have taken part in brief walkouts at plants across Germany since pay talks between the union and employers broke down last week, according to Reuters.

IG Metall, which represents 3.5 million workers in the engineering and manufacturing sector is demanding a 4% pay rise and has rejected an offer from employers of two separate rises of 1.2% over 27 months. It also rejects employer demands on changes to rules on working hours.

A union spokeswoman told Reuters stoppages would be held across Germany at various times during the day while a Ford Europe spokesman said some 10,000 workers had stopped work for about an hour at the group's plant in Cologne, where IG Metall held a demonstration.

The union also reportedly said up to 1,000 demonstrators were expected to gather outside Porsche's headquarters in the Stuttgart suburb of Zuffenhausen while workers would also down tools at DaimlerChrysler's factory in nearby Sindelfingen.

Reuters said talks in Baden-Wuerttemberg, which traditionally leads pay negotiations for the rest of Germany and where both DaimlerChrysler and Porsche are based, are due to resume on Thursday with several rounds of talks in other regions planned in the coming weeks.

The news agency noted that employers are asking workers to accept variable hours to match demand but IG Metall says that would represent the return of the 40-hour week and would amount to a 17.5% cut in wages and could also cost hundreds of thousands of jobs.