F1 managing director Ross Brawn said: "If a team is prevented from entering a country, we can't have a race.

"Not a World Championship race, anyway, because that would be unfair."

Vietnam has imposed a 14-day quarantine period on visitors from Italy, while Bahrain has employed special measures to ensure its race can go ahead.

The Bahrain and Vietnam Grands Prix are scheduled to be the second and third events of a season that starts in Melbourne, Australia on 13-15 March.

On Wednesday, Martin Palmer, minister for tourism, sport and major events in the state of Victoria, said he was "hopeful and confident the Australian Grand Prix would go ahead, but I can't say anything with absolute certainty".

Authorities in Bahrain, whose Grand Prix is on 20-22 March, have imposed 14-day quarantine on travellers from a number of countries where virus outbreaks are most severe, including Italy, home of Ferrari.

But Bahrain authorities are planning an expedited screening process for F1 personnel to limit the effect of restrictions.

F1 says it is working on introducing a similar arrangement in Vietnam, where the quarantine period for travellers who have been to Italy in the previous 14 days is a threat to the race on 3-5 April as it would effectively mean personnel from the Ferrari and Alpha Tauri teams, as well as tyre supplier Pirelli, would not be able to enter the country.

Brawn told Reuters: "Obviously if a team makes its own choice not to go to a race, that's their decision.

"But where a team is prevented from going to a race because of a decision of the country then it's difficult to have a fair competition."

Brawn said F1 was negotiating with the Vietnamese health authorities.

"They want the race to happen but also they've got to protect their population," he said. "So we're looking at what solutions we can find to make sure everybody is comfortable with the arrangements.

"There's a lot of things going on at the moment and it changes on a day-by-day basis. It's difficult to be definitive now but we're going to find solutions."

An F1 spokesman said the event in Hanoi was "going ahead at the moment".

What is Bahrain doing?

Bahrain immigration and health authorities have requested the names and flight details of all F1 personnel who work for teams, administrators, broadcasters or media who have been to, or transited through, China (including Hong Kong), Iran, Iraq, Italy, Japan, South Korea, Malaysia, Singapore, Egypt, Lebanon and Thailand in the 14 days before their arrival in Bahrain.

This is in addition to the names and flight details of all passengers planning to arrive in Bahrain via the United Arab Emirates.

These passengers are expected to be screened at Manama airport on arrival and if they are clear of the coronavirus will be allowed to enter the country.

What do Italian F1 personnel say?

Ferrari said they were planning to go to Australia and Bahrain as normal and were not expecting any problems but that they would have to "wait and see" how the situation in Vietnam was resolved.

A Pirelli spokesman said: "So far, we follow the indications given by F1. So far, these only underline that in Australia and in Bahrain we Italians (plus other nationalities) will face a medical check once landed there.

"For Vietnam we don't have any indication yet, except that the GP will be held as planned and it will be with us."