Jenson Button has hit back at Flavio Briatore after the Renault boss questioned the Briton's talent during his scathing attack on the credibility of Formula One in the wake of the diffuser row.

Button topped the timesheets in the second session of free practice yesterday as he looks to complete a hat-trick of victories at this weekend's Chinese Grand Prix in Shanghai.

His Brawn GP began the season with the controversial 'double-decker' diffuser that has helped Button to victories in Australia and Malaysia.

The FIA's International Court of Appeal on Wednesday ruled that the component is legal, leaving Renault and six other teams playing catch up to the 'diffuser three' — Brawn, Toyota and Williams.

That prompted Briatore to issue a damning attack on the decision in a interview with Italian newspaper La Gazzetta dello Sport, in which he said: "Our (McLaren, Ferrari and Renault) drivers are or have been world champions.

"Then you have a (Brawn GP) driver who was almost retired, and another who is a 'paracarro' (an Italian term for a concrete roadside post), fighting for the championship."

But Button branded Briatore "bitter" and suggested the Italian should concentrate on improving his own team's car.

"It is very unfair for Flavio to comment as he has just because he is very bitter," said the 29-year-old.

"He should also not forget that he tried to employ me for this season.

"He is obviously a very angry man after the diffuser issues and is very disappointed they have not produced a car that is as competitive as ours."

After finishing behind fellow Brit and current world champion Lewis Hamilton in yesterday morning's practice, Button was on top in the afternoon session.