SOCHI (Russia) • Mercedes team boss Toto Wolff denounced conspiracy theorists as "lunatics" after a Russian Grand Prix in which Nico Rosberg won his seventh race in a row, and team-mate Lewis Hamilton had more engine problems.

Reigning world champion Hamilton himself also insisted that he had no reason to believe any conspiracy was happening, after coming from 10th place in the starting grid to finish second.

Wolff said he was speaking out because the abuse directed at the Formula One team could impact on engineers and other employees.

"I want to ignore this bunch of lunatics who think we would want to harm a driver, who is our driver and who has been a double world champion for us," he said. "He hasn't let us down and we wouldn't let him down. This is a mechanical sport and these things happen. We are pushing the limits on the chassis and on the engine side a lot in order to have a competitive car. This is why we are winning races, but also if you push the limits at a certain stage you find them.

"The reason why I'm being vocal about it is that I want to protect those guys because they're being hit by comments that are just inexcusable and unfair - abusive without any reason.

"In the last couple of races we have made some mistakes and letting Lewis down with the engine is certainly one of them."

Hamilton had put in a gutsy recovery drive. But, having clawed the gap back to 7.5 seconds to Rosberg, he had to back off with a water pressure problem and settle for second.

This poor luck, with his struggles this season a big contrast to Rosberg's problem-free runs, has brought about the rumours online that Mercedes are favouring the German this term.

However, even Hamilton was quick to dismiss talk of favourtism.

He told Sky Sports TV: "All I can say is that my side of the garage are having a hard time. I have every confidence and faith in them. I would like to thank the guys who flew over from the factory and the mechanics who worked until 2am to get my car ready. Without that, I wouldn't have got to this point.

"The water pressure issue just happened and I had to nurse it home. I'm just happy the car finished."

He has not won a race since he took his third title in Texas in October and has suffered mechanical problems in his last two races. He is 43 points behind Rosberg after four races.

REUTERS, AGENCE FRANCE-PRESSE, THE GUARDIAN