"This morning we said our intention is to avoid forced redundancies," Tavares said on Thursday at an auto-industry conference in Berlin. "But again, we need to be very honest."

Ultimately, forced redundancies at Opel can only be avoided "to the extent that the implementation of the plan will deliver results," the CEO said.

Earlier on Thursday, Opel said it will shift its model lineup onto PSA's architecture faster than previously planned, as the French parent pursues 1.7 billion euros ($2 billion) in savings from its acquisition of Opel.

"This gives us a lot of room to improve and make sure that we can deliver all the synergies that are now being created after this acquisition," Tavares said. "In PSA and also in Opel-Vauxhall, the level of waste is still very high."

Separately, the CEO said PSA's European factories are fully utilized.

($1 = 0.8598 euros)

(Reporting by Andreas Cremer; Editing by Arno Schuetze)