Hamilton was left stranded in the pitlane, and Rosberg briefly stuck in the garage, as both drivers prepared to go out for the crucial first runs in the final qualifying segment.

The delays compromised both drivers' qualifying preparations, and Hamilton was convinced that it robbed him of what he believed would have been a pole position run.

Investigations of what went wrong have revealed that the matter related to the higher than normal car temperatures, which meant the fuel was warmer than the car's fuel pump could cope with.

Mercedes motorsport boss Toto Wolff said: "It looks like as a consequence of fuel temperature we had a fuel pump problem, which we had on both cars. And unfortunately Lewis was out of the garage so it took a while to sort.

"But at least we have identified the problem and we have a solution for that. At least this is the information I have."

Wolff said that the situation was triggered by Monaco being a short lap, so the cars did not have enough time to cool down on the slowing down lap.

"The lap is pretty short here and when you are tight on time, the procedure is different here – and that was the root cause," he said.

"It is something that is related to pulling the car back after a short lap – a hot car into the garage and that affects the fuel pump. It shouldn't happen – and normally it does not."

Reliability trend

The issue with the fuel pump is the latest reliability drama to have hit Mercedes this year, which has suffered a spate of MGU-H problems on Hamilton's car.

Wolff believes the frequency of the incidents was related to the team pushing the performance limits as the consequence of increased competition from Red Bull and Ferrari.

When asked if it was a surprise such things were happening, Wolff said: "Yes, especially if you consider the miles we have done in pre-season testing without any problems.

"Of course we are pushing the limits, we are pushing the limits on the car, on the systems and on the engines – and when you push yourself you reach those limits.

"But we just need to sort it out and, with calm and structured processes, and get to the root causes of all of that. Because it starts to get a bit frustrating."

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