The Australian and Chinese Grand Prix have been postponed due to the coronavirus pandemic restrictions in place.
Italy's Imola circuit was added to the 23-race calendar as the second race of the season on April 18, with the third slot on May 2 still to be confirmed.
Australia was given a new date of Nov. 21 for the race in Melbourne.
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China was not listed on the revised calendar but Formula One sources said it would be slotted in if circumstances allowed and another race dropped off. The calendar will not stretch beyond 23 races.
Both the Australian and Chinese races were cancelled entirely last year as the pandemic ripped up the sporting calendar, with the season reduced to 17 grands prix in Europe and the Middle East.
"We are pleased to confirm that the number of races planned for the season remains unchanged," said Formula One's new chief executive Stefano Domenicali in a statement.
"The global pandemic has not yet allowed life to return to normal, but we showed in 2020 that we can race safely as the first international sport to return and we have the experience and plans in place to deliver on our season.
"It is great news that we have already been able to agree a rescheduled date for the Australian Grand Prix in November and are continuing to work with our Chinese colleagues to find a solution to race there in 2021 if something changes.
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