The IG Metall metalworkers union is reported to have demanded that Volkswagen set out a detailed reorganisation plan before the union decides whether to reopen a contract that bars German layoffs through 2011.

"Volkswagen now has to lay its cards on the table. We want to know where the company sees the need to restructure and what steps it aims to take," Hartmut Meine, the union's chief negotiator, told the Reuters news agency.

VW has said up to 20,000 jobs at its six western German factories are at risk from the reorganisation that seeks to make its car and parts plants more competitive but it has not presented many details for the proposed revamp, according to the report.

Meine reportedly said the union expected VW to present an overall plan for maintaining plants and workers in the long run.

"The real problems at Volkswagen and their causes may not be allowed to fall under the table," he told Reuters.

He reportedly reiterated IG Metall's comment that VW workers were not prepared to accept an "orgy of sacrifice" and that the restructuring programme had to balance productivity gains and employment guarantees fairly.

Reuters noted that VW brand head Wolfgang Bernhard has said sweeping cost cuts were needed to ensure Volkswagen's long-term competitiveness, and has refused to rule out closing some operations.

He recently annoyed workers by saying 1,200 jobs at the main VW plant in Wolfsburg would go when production of the current 'Mark IV' Golf estate car (station wagon) ends and production of its successor begins in Mexico, alongside the Jetta and New Beetle.

German production of the Bora, the Jetta's predecessor, also ended recently.

According to Reuters, Bernhard has said a cost-cutting deal with workers should be in place by year's end, a target critics say is too far off.