One of Robert Kubica's major sponsors has confirmed it will talk to Williams about the decision to retire Robert Kubica from last weekend's Russian Grand Prix in order to save car parts.

Kubica was told to bring his car into the pits one lap after teammate George Russell crashed out of the race in Sochi due to a failure on the front of his car.

Kubica had been running 16th at the time, with the team's official comment being: "Robert’s retirement was a team decision to conserve parts as we weren’t in contention for points." The Polish driver admitted in the media pen soon after being parked he was uncertain why the decision to retire had been taken.

The call may have landed Williams in hot water with one of its sponsors, though. PKN Orlen is a major backer for Kubica, and enjoys significant coverage on Williams' car, most notably on the rear wing.

PKN Orlen spokeswoman Joanna Zakrzewska confirmed via Twitter that the company would be discussing the reasons behind the decision to retire Kubica in Russia with Williams.

"In connection with the withdrawal of Robert Kubica from Sunday's race as part of the Russian Grand Prix, we have officially asked the ROKiT Williams Racing team for clarification," Zakrzewska wrote.

"Based on them, we will take actions related to the enforcement of obligations under the contract."

Kubica has already confirmed his exit from Williams at the end of the 2019 season, having scored the team's only point so far this year at the German Grand Prix in July.