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 hattrick 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 newspaper interview, 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.

‘‘We have produced as competitive a car as we have because of the workforce back in Brackley and you cannot take that away from them.

‘‘It is unfair to say that as they have worked very, very hard in difficult circumstances.’’ The row also prompted a response from Formula One supremo Bernie Ecclestone, who suggested Briatore should concentrate solely on race matters.

‘‘Its a pity they don’t talk more about racing than politics,’’ he said. ‘‘We seem to have got a lot of team managers who’ve become politicians.’’ But despite the off-circuit distractions, Button remains focused on continuing his dream start to the season with a victory in Shanghai.

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

A win this weekend would add to what is already his best season in Formula One but despite a couple of frustrating years, where he has predominantly toiled at the back of the grid, Button insists his passion for the sport has never wavered.

‘‘We have finally produced a car that is competitive and we are getting the best out of it,”

he said.

“It is not our fault that we have a good car.

‘‘Things change in Formula One and we have seen change. Some people might not be happy about it but instead of getting angry they should concentrate on improving and catching us up.’’ Meanwhile, Hamilton has expressed his surprise at Ron Dennis’ decision to sever all ties with Formula One.

Dennis mentored Hamilton from his karting days through to becoming the 2008 world champion, but after taking a back seat earlier this year, the 61-year-old this week stepped down from his role as chief executive of McLaren Racing.

It was a disappointing end to his 28-year reign at McLaren, with the team struggling to compete this season while also being embroiled in controversy after they were found guilty of misleading stewards at the season- opening Australian Grand Prix.

McLaren have been called before the FIA’s World Motor Sport Council on April 29 to answer charges of bringing Formula One into disrepute for that incident, and Hamilton admitted he was surprised that Dennis chose to step down when he did.

‘‘I wasn’t disappointed, I was surprised,’’ said the 24- year-old. ‘‘I hadn’t heard about it, I was just as surprised as the rest of the team.

‘‘Ron has been a huge force and support in my life and still plays a key role.

‘‘You guys have been writing about it for years – as soon as he gets to a certain stage he was going to move aside and he decided to do it now.’’ After the FIA’s International Court of Appeal ruled the controversial ’double-decker’ diffuser legal on Wednesday, McLaren were quick to try a revised component on Hamilton’s car in practice yesterday.

The defending champion showed something like his past form by going on to top the timesheets in first practice ahead of Button.

Hamilton’s future at McLaren has been subjected to scrutiny since Melbourne but the Stevenage man yesterday insisted he was happy at the team, although he stopped short of making a firm commitment for the future.