World champion Sebastian Vettel's hopes of becoming the first repeat winner of the Formula One season vanished on Sunday when he retired from the European Grand Prix in Valencia while leading from pole position.

The German was on course for a hat-trick of wins in the Spanish port city, after winning in 2010 and 2011, when his Red Bull suddenly lost power after racing had restarted following a safety car period.

The champion stepped out of his stricken car and angrily threw a glove at the wall while Red Bull designer and technical head Adrian Newey, watching on the team pit wall, buried his head in his hands in despair.

"I lost drive on the straight down to turn 17 and I had to give way to the other people," Vettel, who had romped away at the start to build a comfortable lead until the safety car appeared, told the BBC.

"The engine stalled and switched off and there was nothing we could have done. At the moment it's not clear what exactly was the problem."

The safety car was deployed after tyre and wheel debris was left on the track after a coming together between the Caterham of Heikki Kovalainen and Toro Rosso of Frenchman Jean-Eric Vergne.

Vettel left Ferrari's Fernando Alonso in first place, to the delight of the home fans.

Frenchman Romain Grosjean, who had hoped to become the eighth different winner in eight races, then retired when his Lotus suffered an alternator problem while challenging the Ferrari for the lead.