The first four Classics of the 2020 Flat season in Britain will be pushed back until later in the campaign due to the coronavirus pandemic.
Jockey Club Racecourses, which owns both Newmarket, which hosts the 1000 and 2000 Guineas, and Epsom, the home of Derby and Oaks, has announced the fixtures will not take place on their scheduled dates in May and June.
The Guineas meeting was due to take place on May 2 and 3, with the Derby fixture following on June 5 and 6, but the races will now be rescheduled "once racing has resumed in Britain".
Amy Starkey, who is responsible for Newmarket as JCR's East Regional Director, said: "With less than a month until the Qipco Guineas Festival, trainers need to know whether to step up preparations for their Guineas horses or put that on pause for a later date.
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"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, in conjunction with the British Horseracing Authority, participants and stakeholders, the earliest possible opportunity to reschedule the 2000 Guineas and the 1000 Guineas."
Phil White, who runs Epsom as London Regional Director, said: "Following consultation with our many event stakeholders and in order to comply with current government guidance, given the unique nature of the Downs as a public space, sadly it is not practical to stage the Investec Derby Festival on June 5 and 6.
"We are now working with the sport to explore our options to reschedule, at minimum, the Derby and Oaks, as part of delivering the 2020 Classic programme for three-year-olds.
"We thank all involved for their pragmatism and patience as we work this through together."