General Motors' loss-making European brand Opel is currently running at 70 percent capacity in three-shift operation, Opel production chief Peter Thom said, dismissing press reports that it was far lower.

"In two-shift operation, utilization is around 100 percent," he told Reuters on Wednesday.

Given the high amount of fixed costs when manufacturing cars, the utilization of existing production capacity in factories is a crucial determining factor for earnings.

German press had recently reported Opel plants in Europe were running at half their capacity, far below the 80-85 percent generally needed for a carmaker to be profitable.

Earlier, GM pledged to invest 4 billion euros ($5.2 billion) in Opel by the end of 2016 to support new model launches.

($1 = 0.7658 euros)

(Reporting By Christiaan Hetzner)