London: The fallout between Red Bull and Renault shows no sign of easing as the team have now been accused of "lies" by their power-unit supplier.
After four years of success from 2010-2013, when Red Bull and Renault swept aside their rivals to lay claim to the constructors' and drivers' titles over that period, the pair have now resorted to public mud-slinging.
Renault has struggled to cope with last year's change to the rules and the introduction of the 1.6-litre V6 turbo-charged power unit. In turn, Red Bull have struggled to cope with being second rate, in particular as rivals Mercedes have now taken over the dominant role.
Following the recent season-opening Australian GP, the Red Bull hierarchy tore into Renault as belief over the winter they would close the gap to Mercedes was left in tatters in Melbourne.
Team principal Christian Horner claimed Renault's power unit was "undriveable" and 100bhp down on that of Mercedes. Chief technical officer Adrian Newey added there to be "no light at the end of the tunnel" with regard to a power unit that possesses "all sorts of failings".
In response, Renault managing director Cyril Abiteboul has come out swinging in an article in French magazine Auto Hebdo, notably at Newey.
Asked about the comments from Newey, the most successful designer in F1's history, Abiteboul replied: "It's hard to have a partner who lies. Adrian is a charming gentleman and an outstanding engineer, but he has spent his life criticising his engine manufacturers. He's too old to change."
Abiteboul does at least concede to Renault's failings due to a number of late technical developments which have not worked. Far from making excuses, Abiteboul admits the current situation to be "scandalous, frustrating, sad".