A shortage of antigen tests has prompted the British Horseracing Authority to "temporarily" defer the requirement for jockeys to show proof of a negative result before entering the weighing room.
The change in protocol was due to come into force on Wednesday, with everyone entering the weighing room complex on racedays asked to show evidence of a negative test.
However, a statement from the BHA on Saturday said: "Recognising the difficulty some participants and officials have had in ordering lateral flow tests (LFTs), the racing industry Covid-19 Group has temporarily deferred the requirement, announced earlier this week, to show a negative lateral flow test to gain entry to the weighing room, which was due to take effect at all fixtures from 5 January.
"Existing requirements will remain in place, including the need for Covid status certification for all weighing room attendees at all fixtures. Anyone unable to provide evidence of vaccination status will continue to require proof of a negative PCR or LFT test."
A new implementation date will be announced when "LFT supply issues improve".