Robert Kubica has cancelled his 2017 World Endurance Racing programme with the LMP1 ByKolles outfit.
The former F1 driver had been scheduled to return full-time to circuit racing this season with the private WEC team following a test at the end of last year.
Just days before the series gets underway at Silverstone, Kubica had a change of heart, announcing on social media that he would not be racing with ByKolles.
"After the prologue [test], I have decided to interrupt my racing programme with the ByKolles team in LMP1," Kubica said in the statement.
"Therefore, I will not take part in the upcoming WEC Silverstone opening round and in the other WEC races.
"It has been a hard decision to step down and to lose the opportunity to join such a challenging and competitive championship, but I hope this will not be a definitive goodbye."
The details of Kubica's decision are not known but ByKolles endured a difficult time at the WEC prologue test in Monza recently.
Its ENSO CLM P1/01 missing the first two sessions and only completing six laps on the Saturday evening - with Oliver Webb driving - before problems halted the team's test.
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