Valtteri Bottas has lost his major personal sponsor.

Billionaire Antti Aarnio-Wihuri, boss of the Finnish conglomerate Wihuri, told Ilta Sanomat newspaper that sponsoring formula one has become "too expensive".

He also admitted that Bottas' poor performance at Mercedes last year was another reason for the decision.

"Partly it was not his own fault, but I think he was quite weak at the end of the year," Aarnio-Wihuri said.

"It's difficult to be Hamilton's teammate, but Valtteri was also left behind by many others. It was a pretty weak result," he added.

Aarnio-Wihuri has sponsored Bottas, 29, for his entire racing career.

Bottas' business manager Ville Ahtiainen told the Finnish broadcaster MTV that losing Wihuri is not the end of the world.

"Wihuri was a great supporter of Valtteri's journey, but we are in a really good situation," he said.

"Pretty soon there will be good announcements on the partner side. This does not affect Valtteri's situation in any way."

Aarnio-Wihuri agrees with that, saying that while Bottas is "a little sad" about the news, "he understands".

"He's at a stage in his career where he earns enough to succeed. He doesn't need it," he said.