Formula One will not visit Azerbaijan, Singapore or Japan this year but organisers remain confident of staging between 15 and 18 grands prix.
F1 announced on Friday morning that it would not be possible to put on races this year on the street circuits in Baku and Singapore, nor at Suzuka.
A statement read: "As a result of the ongoing challenges presented by Covid-19, we and our promoters in Azerbaijan, Singapore and Japan have taken the decision to cancel their races for the 2020 season.
"These decisions have been taken due to the different challenges our promoters face in those countries. In Singapore and Azerbaijan the long lead times required to construct street circuits made hosting the events during a period of uncertainty impossible and in Japan, ongoing travel restrictions also led to the decision not to proceed with the race."
As for the prospect of replacing those venues with new locations, the announcement continued: "We have made significant progress with existing and new promoters on the revised calendar and have been particularly encouraged by the interest that has been shown by new venues in hosting a Formula One race during the 2020 season.
"We appreciate this is still a time of uncertainty and complexity around the world and will continue to ensure we proceed with the 2020 season in a cautious and flexible way. We have detailed and robust safety plans in place to ensure we begin our season in the safest possible way."
Earlier this month an eight-race European calendar was unveiled to get the delayed 2020 season under way, but the plan is to add a further seven to 10 events before the end of the year.
It is hoped the full calendar will be finalised before the season-opening race at Austria's Red Bull Ring on July 5.
That grand prix will be the first of two races on consecutive weekends at the track in Spielberg, before a Hungarian Grand Prix on July 19 and two races at Silverstone on August 2 and 9.
Further races will follow in Spain, Belgium and Italy - with eight races the minimum needed to determine a world champion.
F1 had then been hoping to shift to Asia and the Americas, but managing director Ross Brawn on Thursday suggested further European races could be added due to the difficulty of organising events around the world as nations come through the coronavirus pandemic at different rates.
"There is a contingency to have an extended European season with another one or two races if needed," Brawn said on the F1 website. "I think Bahrain and Abu Dhabi will be the backstop of the season from what we can see at the moment.
"That gives us 10. We'll find at least five or six good races in the middle."
Circuits including Italy's Imola, Portugal's Portimao and Germany's Hockenheim would come under consideration if the European campaign is extended.
"There are a number of good European tracks where we could add another one or two races on to make sure we have a comprehensive season," Brawn said.
"We're not going to declare it yet, as it's still a work in progress."