British Horseracing Authority officials have announced no new positive cases of equine influenza have been detected among more than 700 samples so far processed.

All race meetings in Britain have been cancelled until Wednesday after six cases of equine flu were confirmed on Friday at the stables of trainer Donald McCain.

The equine flu is the same strain that shut down racing in Australia in 2007, according to Sky News.

Up to 10,000 horses in Australia were affected by the north American strain known as Florida Clade 1 during the six-month outbreak.

In an update on Saturday afternoon, the BHA reported the Animal Health Trust in Newmarket had found “no further positive samples”.

“The AHT has informed the BHA that it has received approximately 2100 nasal swabs and tested and reported on 720. So far, other than the six at the yard of Donald McCain already identified, there have been no further positive samples returned,” the BHA's statement read.

“This includes the swabs taken from horses at the yard of Rebecca Menzies. One horse – which tested negative – had previously been identified as suspicious and high risk after testing at a different laboratory.

“All these horses will remain under close surveillance, analysis of tests from the yard is ongoing – and testing of the suspicious horses will be repeated.”

The BHA announced the cancellation of three meetings on Thursday because of the flu outbreak, and then swiftly imposed a six-day shutdown of the sport until Wednesday at the earliest.

The governing body is due to decide on Monday whether a Wednesday resumption is still feasible.

Hopes that it might be appeared to recede when it became apparent on Friday night a second yard, Menzies' in Durham, was potentially affected by the virus, which is confirmed as the FC1 North American strain.

And while Saturday's initial all-clear on those horses appears much more encouraging, the BHA also warns there will be further re-testing – and many more samples remain to be examined from more than 170 yards which might have come into contact with the infection.

The BHA's swift and uncompromising response to the outbreak at first received universal industry support.

However, there has since been dissension in the ranks from high-profile trainers Nigel Twiston-Davies and Colin Tizzard – who voiced their frustration at what they believe is an “overreaction” to abandon all domestic fixtures for six days.

As for any potential resumption, the BHA indicated feature races lost this weekend at Newbury and Warwick may yet take place at a later date – and that plans for next month's Cheltenham Festival, the highlight of the jumps calendar, remain as yet unaffected.

The four-day Cheltenham event, the fourth most attended sporting event in Britain which attracts over 320,000 visitors, is due to start on March 12.

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