Rueselsheim, Germany - Thousands of workers employed by General Motors in Europe took to the streets Thursday to demonstrate against the giant US carmaker's sweeping restructuring plans and to save their jobs.

The protests came as GM's German offshoot Opel prepared to unveil a rescue plan for the German operations and the government in Berlin stepped up its criticism of the US-based auto group amid a deepening crisis in the global car industry.

German Economics Minister Karl-Theodor zu Guttenberg lashed out Thursday at the Detroit-based GM, criticising the company for failing to provide adequate information about future business plan for Opel.

The German Economics Minister said up until now both potential investors and the German Government still did not know what the GM group planned for Opel, which is expected to unveil a rescue plan possibly on Friday.

This, Opel hopes, will pave the way for Berlin to provide the struggling carmaker with a reported 3.3 billion euros (4.3 billion dollars) in government-backed loan guarantees to help it through the current crisis.

But the European Commission warned Thursday that it would take action to head off countries providing what it considered to be unfair support to their national car sectors.

In addition to Germany, GM has operations in Britain, Spain and Sweden. However, GM's Swedish SAAB company has already filed for bankruptcy protection.

As part of the plans under consideration by Opel, the auto group is also weighing up breaking away completely from its troubled US parent that is threatened with insolvency despite 17.4 billion dollars Washington lent GM and rival Chrysler last year.

GM's far-reaching restructuring plans include big job cuts worldwide and could result in its hiving off parts of its international operations.

German carmakers including Volkswagen, BMW and Daimler, the manufacturer of luxury Mercedes-Benz cars have already cut production and placed employees on reduced working hours as they face up to the global economic slowdown.

Carrying placards saying "No closures in Europe", up to 15,000 demonstrators turned up for the rally held at Opel's German headquarters in the western city of Ruesselsheim.

The worldwide overcapacity in the car industry was no reason for shutting Opel in Germany, a representative of the IG Metall union Armin Schild told German radio Thursday. (dpa)