Troubled German carmaker Opel, under pressure from US parent General Motors to drive back to profit, will cut working hours at a third plant, the head of the works' council said Friday.

A day after Opel announced it would introduce short-time work at its German plants in Ruesselsheim and Kaiserslautern from September, the head of the works' council said Eisenach plant would also be affected.

"We have given our agreement for several short-time shifts," Harald Lieske told AFP.

The move will affect 10 morning shifts and 10 afternoon shifts and would run from next month until the end of the year, he added.

Opel employs 1,800 workers at the Eisenach plant in central Germany where its Corsa model is produced.

Around half of the 22,100 people who work at Opel's four production plants in Germany are now hit by short-time work schemes.

Under such plans, employees see their working hours reduced for a limited period, but the state, in the form of the Federal Labour Agency, partially makes up for the corresponding shortfall in pay.

The measure was used widely by German companies, including Opel, during the crisis of 2008-2009, helped avoid widespread layoffs and allowed companies to ramp their operations up again quickly when demand recovered.