While the ban has been lifted in Ireland, four new cases of the disease have been discovered in the UK, potentially hampering hopes British horse racing could resume this week after it was stopped for several days in a bid to stop the illness spreading.
It had been thought the sport would restart on Wednesday.
The racing world was rocked last Wednesday after it emerged three horses - which subsequently rose to six - were found to have the highly-infectious disease at Donald McCain's stable in Cheshire.
The ruling body quickly enforced a six-day shutdown of racing in Britain, but the IHRB confirmed racing would continue in Ireland - with all runners from Britain not permitted to race until further notice.
With the British Horse racing Authority (BHA) due to decide late on Monday whether racing can resume in Britain on Wednesday, the Irish Horse Racing Board (IHRB) said British horses would be allowed to run again in the country, provided they have been vaccinated for equine influenza which contains Clade 1 virus within eight weeks of their race and they are not from yards which are under BHA restrictions following the outbreak.