Ferrari has hit back at Max Verstappen's 'cheating' claims made against the Italian team following the United States Grand Prix.

Dutchman Verstappen, who finished third behind the Mercedes duo of Valtteri Bottas and newly-crowned six-time champion Lewis Hamilton, said Ferrari had lost their previous speed and form because they had been stopped from cheating by an official technical directive.

The directive, from the sport's ruling body, the International Motoring Federation (FIA), followed an inquiry from Vertappen's Red Bull about a 'tricky' fuel-flow system, designed to boost power, that was declared illegal.

Speaking to reporters late Sunday at the Circuit of the Americas in Austin, Ferrari team chief Mattia Binotto said: "I read and I heard a lot of comments this weekend about a technical directive and the impact on our cars.

"I heard comments at the end of the race, which I feel were very disappointing...

"It is the type of comments that are completely wrong in the sport. It is not good for the sport and I think everybody should be a bit more cautious."

Binotto, who celebrated his 50th birthday on race day Sunday, went on to launch a defence of his team, explaining how their six-race run of pole positions came to an end and why they endured a disappointing race with an apparent loss of their previous big speed advantage on the straights.

Ferrari's Sebastian Vettel retired early with broken suspension and teammate Charles Leclerc, powered by an 'old' Spec 2 engine, finished fourth, 50 seconds adrift of Verstappen's Red Bull. Asked why he thought Ferrari had suffered a slump, Verstappen said: "That's what happens when you stop cheating..."

Binotto rejected the charge, saying: "As a matter of fact, I believe we were very close to pole position as it was in the last race. I think Seb could have scored pole, but maybe was a bit too cautious in one corner."

He said Leclerc faced technical difficulties without which "he was potentially on the pole as well. So, I don't see where is the problem..."

He explained that Ferrari changed their base set-up and ran with more down-force - a switch that helped them gain in the corners, but at the cost of speed on the straights.

Copyright Agence France-Presse, 2019