MONACO (REUTERS, AFP) - Nico Rosberg took a surprise hat-trick of Monaco Grand Prix victories on Sunday, after Mercedes blew championship-leading team mate Lewis Hamilton's chances with a late pit stop while he was leading.

The result, with Hamilton third after leading for 64 of the 78 laps after starting on pole, slashed the Briton's lead over German rival Rosberg to 10 points after six of 19 races. Ferrari's Sebastian Vettel finished second.

Hamilton's race unravelled when the safety car was deployed after Dutch 17-year-old Max Verstappen crashed heavily into the barriers.

While the race leader pitted for fresh tyres, Rosberg and Vettel stayed out.

"I've lost the race haven't I," the disconsolate double Formula One world champion enquired over the team radio after rejoining in third place. "What's happened guys?"

Hamilton's team were swift to apologise for the misjudgment, but their actions had deprived him, and the spectators, of a fair sporting outcome after he had dominated the 62nd running of this classic contest.

Rosberg's triumph enabled him to join Briton Graham Hill, Frenchman Alain Prost and Brazilian Ayrton Senna in completing a Monaco hat-trick.