JEREZ, Spain (Reuters) - Lewis Hamilton's first day of Formula One testing with Mercedes ended after 15 laps on Wednesday when his car suffered brake problems and ploughed into a tyre wall.

McLaren Formula One driver Lewis Hamilton of Britain drives during the qualifying session of the Brazilian F1 Grand Prix at Interlagos circuit in Sao Paulo November 24, 2012. REUTERS/Nacho Doce

The 2008 world champion was unhurt in the crash, at the Jerez circuit's Dry Sack corner made notorious in 1997 when title rivals Michael Schumacher and Jacques Villeneuve collided there in the decisive 1997 European Grand Prix.

The car's wheel tracks showed Hamilton had been a mere passenger with no response from the steering as it went off the track.

"Lewis suffered a loss of rear brake pressure, the front brakes enabled him to slow the car but he couldn't avoid the barrier," said Mercedes.

"We have traced the problem to the hydraulic brake line connecting to the right-rear calliper," the team added on their Twitter feed.

The front left suspension and aerodynamic parts were damaged in the impact and a spokeswoman said the car would not go out again on Wednesday because of the time needed to repair it.

Hamilton, 28, had been second fastest with a best lap of one minute 19.519 seconds when he brought out the red flags an hour and 48 minutes into the session.

The Briton is opening a new chapter in his Formula One career with Mercedes after six years in F1 with regular title contenders McLaren, the team that had backed him from his early teenage years in karting.

Mercedes have one win, last year's Chinese Grand Prix, to their credit since buying the championship-winning Brawn team in 2009 and Hamilton has replaced retired seven-times world champion Schumacher.

The British-based team had a difficult start to the first pre-season test of 2013 on Tuesday when Germany's Nico Rosberg completed only 14 laps.

Problems with the car's wiring loom left Rosberg stranded on the track, with flames flaring briefly around the rear of the vehicle, before Mercedes called an early halt to proceedings.

For the second day in a row, the car was returned to the garage on Wednesday on the back of a flat-bed truck for the mechanics to repair.

(Editing by Clare Fallon)

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