FILE PHOTO: Volkswagen CEO Matthias Mueller attends the opening of the Frankfurt Motor Show (IAA) in Frankfurt, Germany September 11, 2017. REUTERS/Kai Pfaffenbach/File Photo

LINZ, Austria (Reuters) - Volkswagen VOWG_p.DE Chairman Hans Dieter Poetsch said on Monday there is no reason to question the position of the carmaker's top executive.

Sources close to the top management of Europe’s largest automaker have told Reuters that Chief Executive Matthias Mueller was growing frustrated by a lack of support for his reform efforts and by the company’s inability to draw a line under its emissions scandal.

But Poetsch sought to stifle any speculation about Mueller potentially growing weary of office. The contract of the 64-year-old Mueller, who took the reins at Volkswagen (VW) a week after the “dieselgate” scandal was revealed, will expire in 2020.

“Now is not the right occasion to say something about this,” Poetsch told reporters late on Monday at a business event in Linz, Austria. “I believe there is also no background to this.”

VW has struggled to rebuild its reputation after admitting in 2015 that it had cheated exhaust emissions tests, a task that was made harder by revelations earlier this year about how the carmaker exposed monkeys to toxic exhaust fumes.

Nearly two-and-a-half years after the “dieselgate” scandal, VW is grappling with investigations and lawsuits around the world and about $30 billion in fines and costs for the fraud just as it pushes a multi-billion strategic shift to electric and self-driving cars.

Despite the challenges, VW seems to be succeeding in putting the scandal behind it as far as the consumer market is concerned.

Sales of the core VW brand set a new record at 6.23 million cars last year and VW said earlier on Monday that its deliveries jumped 7.1 percent in January.

“It has become clear meanwhile that the company is on a very successful path operationally,” said Poetsch, VW’s former long-time finance chief. VW is expected to release core 2017 financial results later this month.