Mark Webber has suggested that Mercedes's rivals are not quite ready to pounce on the German team's dominance.

The Australian's former team, Red Bull, have sped past Ferrari in recent races, with Max Verstappen the only non-Mercedes driver in 2016 to have won a race.

"They're making ground on Mercedes," Webber, now a sports car driver for Porsche, told Germany's Auto Bild. "But I don't see that they have really caught up.

"They have a good race here and there, but Mercedes is usually still unbeatable. But Red Bull is ahead of Ferrari."

Indeed, the 39-year-old joined others in declaring Ferrari's showing in 2016 as a "great disappointment".

"Sebastian [Vettel] and Kimi [Raikkonen] are doing what they can," he said. "They're protecting the team a lot in the media, but inside they'll know that the team needs to get better.

"I think if every week they can make the most of their potential with penalties or strategy mistakes, it's frustrating for the drivers."

Asked if his old teammate Vettel has the ability to push Ferrari forwards, Webber answered: "There's no doubt he can. But he needs the right people and I'm not sure if they have them at the moment.

"Ferrari is under constant media pressure, always needing to deliver. You can see with Sebastian that it can be frustrating, but his experience will help him."

Meanwhile, another of Webber's former teammates, Nico Rosberg, has been passed in the championship battle by the other Mercedes driver Lewis Hamilton.

Asked what the German needs to do now, Webber answered: "Fight like a stray dog! It's a very long season, so he needs to divide his energy and strike with Lewis has another tricky moment."

The season continues next weekend with the Belgian Grand Prix.