Nov.29 (GMM) Martin Whitmarsh has admitted he is not sure if Mercedes will supply a "competitive" engine in 2014.

According to the paddock grapevine, the German manufacturer has an early performance head-start over its turbo V6-producing rivals Renault and Ferrari.

But McLaren boss Whitmarsh, whose Woking based team will switch to works Honda power for 2015, said the rumours Mercedes will lead the game in 2014 cannot be verified.

"Will we have a competitive drivetrain (in 2014)? I don't know," he is quoted by Speed Week.

"There are many people in the paddock who seem to know, but I don't know where they could have got that information from," added Whitmarsh.

"From what I know about Mercedes' resources and organisation, I am assuming that they have done a good job," he said.

"I believe that we will be competitive," said Whitmarsh. McLaren finished the 2013 season just fifth, having failed to score even a single podium.