Sebastian Vettel says he has no plans to retire.

At the end of last year, the German was criticised for making mistakes that contributed to Ferrari not winning the world championship.

And now, those same critics are saying Vettel could be challenged in 2019 by his new teammate Charles Leclerc.

"Over the years I've gotten used to dealing with criticism, even if it's not fair," the German told Sport Bild.

However, he says he is not giving up.

"I think it's clear that I'm not in the spring of my career anymore," said Vettel.

"On the other hand, at 31 I still have plenty of time in this sport. Looking back, Michael was even a bit older than me when he won his first title with Ferrari. And Lewis is two years older than me.

"I still have no thoughts of retiring," Vettel added. "On the contrary, I'm doing everything to fulfil my dream of the title with Ferrari. And my family supports me."

So when asked if he has thought about switching to Mercedes, as his mentor Michael Schumacher eventually did, Vettel answered: "No. My goal is to win with Ferrari."

Finally, Vettel confirmed that he put in a good word with Ferrari when it signed up his friend and countryman Pascal Wehrlein as simulator driver.

"I didn't sign his contract, but when the topic came up, I said his name," Vettel said.