Lewis Hamilton says "someone doesn't want" him to win this year's championship, the Briton demanding answers from Mercedes after his engine failure during the Malaysian Grand Prix.
Hamilton looked set for victory at Sepang when his engine blew up with 15 laps remaining, handing championship rival Nico Rosberg a huge advantage with five races left on the calendar.
Rosberg finished third after being spun on the opening lap, but the German now leads by 23 points.
Hamilton said he found it very hard to accept he was the only Mercedes-powered driver to have engine problems.
"My questions are to Mercedes – we have lost so many engines," Hamilton told the BBC after the race. "There are eight drivers and mine are the only ones who has failed.
"Someone has to give me some answers and it is not acceptable.
"Something or someone doesn't want me to win this year."
He added: "It's a brand new engine, I've done one race with it. I did P3 with it, qualifying, it's a brand new engine from the three that I had.
"It's just odd. There's been like 43 engines from Mercedes and only mine have gone."
Hamilton has not won a race since the German Grand Prix and has gone from leading the championship by 19 points to chasing Rosberg by 23.
The world champion insisted he still believes the title is possible, but admitted the problems he has had this year are creating a lot of doubts for him.
"It is what it is, we'll just move forward and try to continue to drive as we had this weekend," he said.
"Right now, I don't even know if my car is going to make it. These next five races, I know that I've got it in us, my engineers and my mechanics, I know we've got it in us.
"But who knows what those next engines that I have are going to do. So I'm just going to keep my head down and hope for the best.
"There's not really much to do. I've just got to move on. The guys did a fantastic job this weekend, and we did everything we could. I did everything I could.
"I just can't believe that there's eight Mercedes cars, and only my engines are the ones that have been going this year. Something just doesn't feel right, but there's nothing I can do about it. Something just doesn't feel right."
Hamilton's regular post-race media debrief has now been called off.
Lowe: No failure is planned
Following Hamilton's comments, Mercedes technical boss Paddy Lowe quickly moved to dispel any suggestions that the engine failure was "planned" or was part of a pattern.
"It is difficult... this can be a very harsh sport," Lowe told Sky. "But no failure is planned. We work as hard as we can to increase reliability and we have, year on year, increased reliability.
"But for some reason, unrelated to any intention or individual performance, a number of things have fallen on Lewis’ car this year. We have eight Mercedes power units this season – and for some reason, there is no pattern as to why they should fall on Lewis’ car. That is how some things turn."
Additional reporting by Andrew van Leeuwen and Jonathan Noble