Jun.24 (GMM) 1997 world champion Jacques Villeneuve has attacked Kimi Raikkonen for struggling to shine in 2014.

After two impressive comeback years with Lotus, Finn Raikkonen was signed for this season by Ferrari, for whom he won his sole title in 2007.

However, two years later Ferrari ousted Raikkonen, and so the news of his 2014 return was a shock to French-Canadian Villeneuve.

"Who would have imagined he even comes back to F1 in the first place?" the 43-year-old told Italy's Omnicorse. "Who would have thought he would return to Ferrari?

"No one -- yet there he is at Maranello."

Villeneuve, however, said 34-year-old Raikkonen - the oldest driver in F1 today - has no right to be blaming the F14-T for his poor season.

"For him, the gas is either fully open or nothing," he said. "He is having a series of spins as though he is in formula 3.

"If he can't drive in F1 anymore, he should go home. He is a very experienced driver," Villeneuve insisted, "so he shouldn't be making excuses at every Grand Prix like a rookie does.

"He should take two or three races to change how he's driving, and if he can't, that's a problem.

"You can't go on like this when you're a world champion. You have no right to make excuses."

Villeneuve has a similarly stark opinion when it comes to Sebastian Vettel, the struggling four-time world champion.

He thinks Red Bull is beginning to turn its back on the highly successful German.

"He is a four-time world champion, but now Red Bull is treating him like they treated Mark Webber. They seem to have decided to focus on Daniel Ricciardo.

"Now they want to 'kill' Sebastian because he's not right for the Red Bull image," he said.

Villeneuve thinks Vettel must be seriously considering a change of team.

"Of course -- you can't have another season like this. Even Helmut Marko has started to criticise him.

"When you lose the faith of the team and the politics starts to weigh heavily, you're finished," he added.