Jockey Club Racecourses (JCR) said they were in talks with the British Horseracing Authority (BHA), participants and partners to reschedule the first four Classics at later dates when racing can resume in the country.
The 2,000 and 1,000 Guineas and the Derby and Oaks were set to take place on May 2-3 and June 5-6 respectively.
"With less than a month until the Guineas Festival, trainers need to know whether to step up preparations for their Guineas horses or put that on pause for a later date," Amy Starkey, East Regional Director for JCR said in a statement.
"The future is too uncertain at the moment and there is no opportunity for any preparation races before such important contests for the 2020 Classic generation.
"Therefore we feel now is the right time to take the decision to cancel the Guineas Festival and turn our attention to determining... the earliest possible opportunity to reschedule the 2,000 Guineas and the 1,000 Guineas."
Phil White, who runs Epsom Downs Racecourse, added: “We are now working with the sport to explore our options to reschedule, at minimum, The Investec Derby and The Investec Oaks, as part of delivering the 2020 Classic programme for three-year-olds."
In a separate statement, Ascot Racecourse said it still hoped to stage this year's Royal Ascot but if the 2020 edition does go ahead it would be behind closed doors.
"For public health and safety reasons we have reached the difficult but unavoidable conclusion that Royal Ascot 2020 (16th - 20th June) will not be able to take place as an event open to the public," it said in a statement.
"It may prove possible to run the Royal Ascot races behind closed doors, dependent on Government and public health policy and the approval of the BHA (British Horseracing Authority) for us to re-start racing."
Last month, the Grand National -- Britain's most iconic horse race and betting bonanza -- was cancelled after the British government withdrew emergency services from supporting mass gatherings.
However, Potter's Corner won a computer-simulated 'virtual' version of the Grand National with 5-1 favourite Tiger Roll coming in fourth in an event that was live-streamed. (Reporting by Rohith Nair in Bengaluru; Editing by Ken Ferris)