Renault could quit F1 or buy Toro Rosso

Renault say they are reviewing all their Formula One options, including quitting the sport or buying the Toro Rosso team, after stinging criticism of their engine.

The French manufacturer has been at loggerheads with main partners Red Bull since Mercedes dominated the season-opening Australian Grand Prix on March 15.

Despite signs of improvement in Friday practice at the Malaysian Grand Prix, Renault Sport F1 managing director Cyril Abiteboul was pulling no punches.

"I can confirm that we are looking at a lot of options, including getting out of Formula One," he told a news conference.

"Honestly, if Formula One is that bad for Renault's reputation, if we see that we will continue to struggle with the current formula, if the sport is not delivering on the value that it costs Renault...

"We think we are a credible player in the sport but you need to think about what else we need to do on top of what we already are. But right now, the focus remains on the engine."

Renault supply engines to former champions Red Bull and sister team Toro Rosso, their only remaining clients after Caterham folded and Lotus switched to Mercedes.

Lotus were previously the championship-winning Renault works team, with the manufacturer selling to Genii capital in 2009-10.

Toro Rosso principal Franz Tost recognised speculation that Renault could buy his team and said it would be a "fantastic opportunity".

"The team wants to be established in the future within the top five of the constructor's championship and to be owned by a manufacturer would be exactly the step forward which the team needs," said Tost.

Renault powered Red Bull to four straight titles with Sebastian Vettel from 2010 but have struggled with the new V6 turbo hybrid engine introduced last year.

The relationship deteriorated further after Melbourne, when Abiteboul took issue with Red Bull designer Adrian Newey's criticism of the engine.

"Let's leave Melbourne behind us," said Abiteboul. "What goes on tour stays on tour...it's not what I said," he added when asked whether he had called Newey a liar.

"Melbourne was extremely frustrating for everyone but already this week it is much better so let's try and stay positive. Let's make sure we continue on that path."

Horner, sitting alongside, hoped Abiteboul had been misquoted and added: "The one thing Adrian Newey is, he's not a liar. He's designed cars that have won 109 victories with Renault power in them."