Volkswagen (VOWG_p.DE) CEO Herbert Diess has developed the right strategy for Europe’s largest carmaker but he must deliver results now in implementing it, labour boss Daniela Cavallo told a newspaper.

“And we do notice that implementation in certain areas is not without friction across brands,” she told Handelsblatt. “But if it’s a company with various brands it’s the management board’s duty to make sure that the brands cooperate more effectively.”

Her comments come after a long-standing conflict between Diess and labour representatives over the pace of reform at the world’s second-largest carmaker escalated this week, with a special committee expected to discuss the CEO’s future at the firm.