Istanbul (AFP) - Reigning world champion Lewis Hamilton was fastest in both of Friday's practice sessions for the Turkish Grand Prix but has to take a 10-place grid penalty for using too many engine parts.

Championship leader Hamilton was quickest in the second practice with a slick 1min 23.804sec ahead of Ferrari's Charles Leclerc, the only other driver to rival him in the session.

Valtteri Bottas in the other Mercedes was third, followed by Red Bull pair Sergio Perez and Max Verstappen.

The session was also notable for Kimi Raikkonen suffering a wardrobe malfunction with a water pump on his one-piece suit flooding his boots.

But earlier Friday British driver Hamilton was given a grid penalty after Mercedes used a fourth new engine part.Just three parts are permitted under the rules.

They are doing this to reduce the risks of Hamilton suffering a failure during a championship run-in that is closer than for years with just two points between the champion and challenger Verstappen.

The team argue they have taken the decision to boost performance. 

Verstappen received a similar penalty two weeks ago.

Because seven-time world champion Hamilton has only taken one power unit component, he will not be punished with a full grid relegation.