Volkswagen's workforce has suffered a major loss of confidence in the German automotive giant's leadership after top management failed to share details about rumoured cost-cutting plans, employee representatives said on Saturday.

Europe's largest carmaker is in uproar over reported cuts of around 100,000 jobs across Germany, with trade union IG Metall holding protests nationwide on Thursday. A supervisory board meeting on the same day ended without confirmation of chief executive Oliver Blume's plans.

Angered at being excluded, the VW works council issued a demand for the release by Friday of full information about what Blume called the "most comprehensive realignment" in Volkswagen's history.

"We strongly condemn the fact that, at the same time, he continues to withhold this information from the tens of thousands of affected employees outside management," the council said in a statement on Saturday.

The works council had demanded that Blume address the workforce by Friday.

"The workforce's main focus will be on whether the Executive Board intends to tackle this crisis by taking the necessary measures together with the employees, or against them," the statement continued.

The details of the cost-cutting package - which was reportedly rejected by the supervisory board - are as yet known only from media reports.

According to Manager Magazin, up to 100,000 jobs could be cut worldwide - twice as many as previously planned. The Bild tabloid reported that the figure could even be as high as 120,000.

Four of the VW Group's plants in Germany are also reportedly under threat of closure, in Hanover, Emden, Zwickau and Neckarsulm.