The workers' union of German carmaker Volkswagen (VW) said on Thursday that its workers would go on extended strikes next week, starting on Monday.

Europe's largest carmaker has faced backlash over its plans to cut wages, layoff workers and close factories for the first time ever in Germany.

The IG Metall union said the strike on Monday would last four hours at nine different sites across the country and on the same day that a fourth round of negotiations between VW and labor representatives will take place.

Thousands of VW employees are also expected to attend a rally on Monday in Wolfsburg, where VW is headquartered.

The planned duration of the work stoppage is twice as long as the first round that they staged this previous Monday, when nearly 100,000 VW factory workers participated.

The company said on Thursday said the management and labor representatives were still engaging in discussions over viable, long-term solutions that balance economic stability and secure employment prospects.

'Layoffs under the Christmas tree'

But the back and forth between the company and labor representatives in public has been far from amicable.

CEO Oliver Blume on Wednesday defended the belt tightening at VW as necessary in a rapidly changing environment, saying management could not operate "in a fantasy world."

IG Metall negotiator Thorsten Gröger responded to Blume's remarks on Thursday. 

"It borders on mockery when Oliver Blume stands in front of the workforce and wishes them a Merry Christmas, while at the same time, the VW board would prefer to put letters of termination under the Christmas tree for the employees," Gröger said.

"We will now step up our efforts on December 9th and thus increase the pressure on the company at the negotiating table," Gröger said in a statement.

Volkswagen has been affected by high manufacturing costs at home, a sluggish shift to electric vehicles and stiff competition from China.

jcg/ab (AP, Reuters)