Fernando Alonso has revealed that, amid the coronavirus pandemic, he suffered "for several weeks" with a mystery illness.

Many have noticed that the almost 39-year-old Spaniard, who is returning to Formula 1 next year with Renault, has appeared visibly thinner in recent weeks.

Alonso admits he was sick "for several weeks".

"I went to the hospital a couple of times, they gave me a lot of tests but in the end we didn't really find out what it was," Spanish reports quote him as saying.

"I tested non-stop for coronavirus but it was always negative," Alonso added.

However, he also told CNN that he is in fact feeling "fresh" after a two-year break from Formula 1.

"I feel fresh now, ready for travelling, ready for doing different things, work on the simulator. So I feel better now than when I was 25," he said.

Alonso told Spanish media that, during his break from F1, he got some calls from Formula 1 teams but "not from Mercedes".

"That is the team with which everyone would sign with their eyes closed because you would immediately have a winning car," he insisted.

It poses the question of why Renault elected to go with its former champion Alonso rather than one of its promising juniors like Christian Lundegaard.

"This should not be regarded as a lack of loyalty to our own project," Abiteboul insists.

"The academy's plan was that one of our young drivers is on the grid in 2021, and maybe this will happen.

"But let's face it: the crisis this year had serious consequences, and one of them is that we cannot yet draw conclusions about the performance of Guanyu Zhou and Christian Lundegaard," Abiteboul explained.