Red Bull issued quit threat to make Renault step up - Christian Horner

Red Bull team principal Christian Horner oversaw all four of the team's constructors' championship triumphs - from 2010 to 2013 inclusive

Red Bull owner Dietrich Mateschitz's threat to quit Formula 1 is an attempt to make Renault improve its engine, says team boss Christian Horner.

Mateschitz said last week Red Bull would quit F1 if they could not get a competitive engine.

Horner said: "If you look carefully at his comments, he is encouraging Renault to step up and do the job properly."

Renault F1 boss Cyril Abiteboul said Renault shared Red Bull's "frustration" at their lack of performance.

Red Bull had another disappointing race in China on Sunday, with Daniil Kvyat retiring with what appeared to be an engine failure and team-mate Daniel Ricciardo finishing ninth.

The Renault engine is uncompetitive when measured against the rival Mercedes and Ferrari units, struggling with both overall power and reliability.

Russian driver Daniil Kvyat retired from the Chinese Grand Prix

Horner said he hoped Renault Sport's engineers at their base in Viry-Chatillon near Paris could find improvements - a major upgrade is expected in early summer, although the date of its arrival has not yet been confirmed.

"There are a lot of talented people in Viry," Horner said. "They have a great heritage and they are better than what we are seeing. It's a question of how you respond to the situation you're in."

He pointed to the progress Ferrari had made over the winter - creating an engine that is almost a match for Mercedes after lagging behind in 2014 - as an example of what was possible.

"It's a long season but hopefully at the end we will look back and say this is a low point but we recovered that situation," Horner said.

"Ferrari in six months since Abu Dhabi have done a super job so it demonstrates what is possible in a relatively short period of time."

Red Bull and Renault won four consecutive drivers' and constructors' titles doubles from 2010-13.

Abiteboul said: "There is no issue with Red Bull, in the sense that they are a team that wants to be extremely successful. They are impatient to be back in a winning position, as we were two years ago.

"So we understand that, and their frustration. We are a supplier but we are also racers and also extremely frustrated.

"It is about supporting each other, not dragging each other down, but we want to deal with it together."