F1's governing body has tightened covid protocols and warned Racing Point amid the unfolding saga involving Lance Stroll's virus infection.

Team boss Otmar Szafnauer defended his actions that led to Stroll admitting this week he had coronavirus after Racing Point said he sat out the Nurburgring with a stomach ache.

"Lance called his doctor," Szafnauer said at the Portimao circuit. "So what should I do? So instead of listening to Otmar he called his doctor."

There are also inconsistencies with Stroll's story, as he said on Thursday that he now feels "great" and only ever had "mild symptoms" - even though he was sidelined in Germany with what the team called a severe stomach upset.

It is understood that Racing Point has been told by the FIA to ensure that covid protocols - which have now been tightened - are strictly followed in future.

Szafnauer says he is "confident" Stroll will return to the pink car on Friday, but Nico Hulkenberg is nonetheless on site and on stand-by for another assignment.

"Nico is here and I think other teams have also opted to bring reserve drivers for the first time," he said. "It just makes sense to have reserve drivers."