Motorsport.com understands that the Moto2 team boss died in his hotel room overnight, however details of his passing are limited at this time.

Police are now investigating Kiefer's death.

The Kiefer Racing squad has opted to withdraw from the Malaysian GP weekend, which means Dominique Aegerter and Tarran Mackenzie won't take part in any of the Sepang action.

"Team manager and owner Stefan Kiefer died unexpectedly on Thursday night," read a statement from the team.

"The circumstances that led to this tragic event are yet to be clarified.

"Out of respect for the entire family and all those involved, the team won't take part in the Malaysian Grand Prix.

"Stefan Kiefer was an active competitor, and after completing his career founded Kiefer Racing with his brother Jochen. Since 2003, Kiefer Racing has been an integral part of the World Championship.

"Due to his friendly and open personality, Stefan Kiefer was a well-loved member of the paddock, and will be painfully missed.

"He leaves behind his partner and his son."

Motorsport.com wishes to extend its condolences to Kiefer's family and everyone involved in the race team.