Sebastian Vettel says a problem with the brakes caused him to collide with Sergio Perez during the closing stages of second free practice for the Bahrain Grand Prix.

The German was leaving the pit-lane for his final laps when he ran up the inside of turn one just as Felipe Nasr and Perez were rounding the corner having just completed their flying laps.

However, Vettel would proceed to clip the Mexican's Force India, damaging his front wing and causing the session to be stopped briefly to clear debris.

Though it was Perez that was initially investigated by stewards for the collision, this was thrown out when Vettel revealed a problem with the Ferrari prevented him from stopping properly.

"I came out of the garage and had a problem," he said. "I hit the brakes but suddenly there was a blow and I couldn't brake properly. Therefore I hit Sergio Perez in the corner. Of course I'm sorry, but I couldn't do anything else in that moment. I was looking for Sergio to say sorry, but he was still sitting in the car."

Vettel would end the day with the fourth fastest time, six tenths down on Nico Rosberg but only a tenth behind Kimi Raikkonen.