Daniel Ricciardo has received high praise from Helmut Marko with the Red Bull advisor saying he is at the same level as Sebastian Vettel.

Having won four consecutive Drivers' Championships with Red Bull, Vettel left for Ferrari at the end of the season, leaving the team with a Ricciardo-Daniil Kvyat partnership.

However, Ricciardo showed what he is cable of during his debut season with the Milton Keynes-based squad as he won three races last season to be the only non-Mercedes driver to reach the top step of the podium.

Marko feels they have a good replacement in Ricciardo.

"Sebastian is clearly a very good and has his merits, but Daniel proved last year that in terms of speed and car development he is of the same calibre," he told Germany's Auto Bild.

Marko and Vettel had an excellent relationship during the latter's stay with Red Bull and that has not changed following the German’s departure.

"There is still contact and I also congratulated him on his victory," Marko said. "I was very happy about it, because there is internal grand prix betting in the paddock and I was the only one who backed Vettel. As such, I had double reason to celebrate!"

Red Bull had a tough 2014 season as Renault struggled to come to grips with the new V6 engine regulations and they haven't improved much this campaign.

"At the beginning we had a problem with our chassis, but we have that fully under control now," Marko said.

"Through the fast corners we are amongst the very best, but what slows us down now is the reliability and performance deficit of the engine.

"This is something Renault needs to work on, and we need to try to help them as much as possible."