Formula One has confirmed the grands prix in Bahrain and Vietnam have been postponed.
Friday's announcement followed the cancellation of this weekend's season-opening Australian Grand Prix.
The Albert Park curtain-raiser was scrapped after McLaren pulled out of the race when a member of their crew tested positive for coronavirus.
The Bahrain Grand Prix had been set to take place on March 22, with the inaugural race in Vietnam scheduled for two weeks later. The Chinese Grand Prix, which would have followed on April 19, was postponed last month.
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In a statement confirming the postponements, F1 said the season is now not expected to start until late May.
The statement read: "In view of the continued global spread of COVID-19 and after ongoing discussions with the FIA, the Bahrain International Circuit, the Bahrain Motor Federarion and the Hanoi People's Committee, the Government of the Socialist Republic of Vietnam, the Automobile Association of Vietnam and the promoter, Vietnam Grand Prix Corporation, a decision has been taken by all parties to postpone both races due to take place on the 20th - 22nd March and April 3rd – 5th April respectively.
"Following the announcement of the Australian Grand Prix's cancellation this week and the ongoing and fluid nature of the COVID-19 situation globally, Formula 1, the FIA and the promoters have taken these decisions in order to ensure the health and safety of the travelling staff, championship participants and fans, which remains our primary concern.
"Formula 1 and the FIA continue to work closely with the race promoters in Bahrain and Vietnam and the local health authorities to monitor the situation and take the appropriate amount of time to study the viability of potential alternative dates for each Grand Prix later in the year should the situation improve.
As a result, Formula 1 and the FIA expect to begin the Championship in Europe at the end of May but given the sharp increase in COVID-19 cases in Europe in recent days, this will be regularly reviewed.#F1
— Formula 1 (@F1) March 13, 2020
"As a result, Formula 1 and the FIA expect to begin the championship in Europe at the end of May but given the sharp increase in COVID-19 cases in Europe in recent days, this will be regularly reviewed."
F1 chairman and CEO Chase Carey said: "The global situation regarding COVID-19 is fluid and very difficult to predict and it's right we take time to assess the situation and make the right decisions.
"We are taking this decision with the FIA and our promoters to ensure the safety of everyone involved in Formula 1 and our fans. The Bahrain Grand Prix is an exciting race in our schedule, and we look forward to being back there as soon as we can. We are also looking forward to Vietnam's inaugural race and bringing the spectacle of F1 to one of the most exciting cities in the world."
FIA president Jean Todt added: "Protecting people first. Together with Formula 1, the Bahrain Motor Federation, the Vietnamese Motorsports Association, and the local promoters, postponing both the Bahrain and Vietnam Grands Prix, as with the Australian Grand Prix, was the only possible decision given all of the information currently available to us.
"We continue to rely on the input and advice from the World Health Organization (WHO) and governments and will work with them throughout this unpredictable period to safeguard the fans, competitors and all of the motor sport community.”