Britain's Lewis Hamilton won a wet Japanese Formula One Grand Prix on Sunday to complete a hat-trick of victories and extend his championship lead over Mercedes teammate Nico Rosberg to 10 points with four races remaining.

Rosberg finished second in a race that needed two starts behind the safety car and ended before the full distance due to a crash that saw Marussia's French driver, Jules Bianchi, rushed to hospital.

"The driver is not conscious and has been sent to the hospital by the ambulance because the helicopter cannot fly in these conditions. Further updates will follow but for the moment we cannot say anything" FIA head of communications, Matteo Bonciani, said.

Later reports stated he had undergone emergency surgery after suffering a "severe head injury" and was in a serious condition.

No champagne was sprayed on the podium and there were no celebrations.

Germany's quadruple world champion, Sebastian Vettel, finished third.

The win was Hamilton's eighth of the season and first at Suzuka, with his only other triumph in Japan coming at the Fuji circuit with McLaren in 2007.

The rain-soaked race was red-flagged with 46 of the scheduled 53 laps completed after an accident involving Sauber's Adrian Sutil and Bianchi brought the safety car out for the third time.

There was immediate concern about Bianchi's condition in the aftermath of the accident, with the medical car and an ambulance immediately dispatched.

"Once I was able to get past Nico I was just able to enjoy the ride," Hamilton said. "It was a great result for the team but obviously I am very concerned about Bianchi right now."

It was a great result for the team but obviously I am very concerned about Bianchi right now."