Nico Rosberg's retirement from the Singapore Grand Prix last weekend was caused after the "steering column electronic circuits were contaminated with a foreign substance," Mercedes has revealed.

Rosberg endured a nightmare race at the Marina Bay Street Circuit and having been unable to leave the grid for the formation lap he then became stuck in neutral at his first stop and was forced out. The DNF cost him the championship lead and he now trails team-mate and Singapore GP winner, Lewis Hamilton by three points.

In a series of tweets, Mercedes explained: "Forensic analysis has revealed that the steering column electronic circuits were contaminated with a foreign substance.

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"The contamination was not visible and did not manifest itself until Sunday as Nico went to the grid.

"The result was an intermittent short circuit in the electronic circuits meaning Nico could not command clutch or engine settings.

"Fresh parts will be used at the forthcoming races. Our hard work on reliability processes will continue at the same intensive level.

"To clarify, the contaminant was a substance used in normal pre-event servicing of the component. #NotAConspiracy :)"

Reliability has been Mercedes' weakness this season, with Rosberg, unsurprisingly, calling for improvement in the wake of what happened in Singapore.