Robert Kubica is still weighing up an offer to race with Manor in the FIA World Endurance Championship through 2018 alongside his reserve driver commitments with Williams in Formula 1, but will decide after an upcoming test for the team.

Kubica took up a reserve role at Williams after missing out on a full-time race seat to Sergey Sirotkin, but has received multiple offers to race in the WEC 'super season' which starts at Spa at the beginning of May.

Kubica attended a three-day test with Manor at Motorland Aragon last month and is due to complete some private running in its new LMP1 car before making a final decision on a WEC programme.

"There is no secret that I have been talking to [Manor]," Kubica said. "I have been in one test with them.  I didn’t go there to watch, but in the end I didn’t drive. We will probably have another go in the next weeks and then we will decide what we are going to do.

"This year will be a busy year for me. From one side I will like to be involved in a good project in LMP1, which will give me a chance to do a lot of kilometres but on the other hand, I do not have a lot of free days.

"Until I spend a few laps behind the wheel I cannot make [up] my mind. It’s not only about making my mind, but if it’s fitting into the busy calendar and a few factors they have to fit together.

"It’s not as simple as yes or not, it’s a bit more complicated."