Renault has "the strongest engine" in Formula 1, according to team boss Cyril Abiteboul.

That is despite the fact that some in the paddock think the French manufacturer has actually fallen behind the ever-improving Honda.

But Abiteboul told Auto Motor und Sport that Renault has made big progress too.

"According to our measurements, we and Ferrari have the strongest engine in the race. Then comes Honda and then Mercedes," the Frenchman said.

But a source at Mercedes has a different view.

"The differences between Honda, Renault and us have become minimal. Only Ferrari stands out," the engineering source said.

And Mercedes' engine boss Andy Cowell said the way the teams measure and compare engine performance - primarily with GPS - is not entirely accurate.

"The engine power is really hard to filter out, especially in the race," he said.