A rift in Continental’s top management resurfaced Monday, just as the car parts maker entered a crunch week in its takeover battle with Schaeffler, the rival that launched a €11.3bn ($16.7bn) bid one month ago.

It has emerged that Hubertus von Grünberg, Conti’s supervisory board chairman, last week urged Manfred Wennemer, chief executive, to include him in the negotiations with Schaeffler’s management, people close to the company said.