Four new positive tests for influenza in horses were conducted in vaccinated thoroughbreds on the Newmarket farm by Flat Trainer Simon Crisford.
Racing is suspended until at least Wednesday, while the British horse racing authority is testing horses across the country.
The suspension came after the discovery of six cases of horse flu in the stable of Donald McCain in Cheshire on Thursday.
Crisford's farm was so named, "the Newmarket community knows where the infection was found," the BHA said.
The yard is one of 174 tested because runners from the stable went into Newcastle on 5 February, which had been identified as potential risk.
All affected horses are in Crisford's yard, the BHA said.
The BHA will announce when races can start again on Monday evening.
The Animal Health Trust (AHT), which conducts tests on behalf of BHA, works with "several thousand samples" obtained from shipyards across the UK.
On Sunday, the BHA reported on Sunday that about 1,500 samples were analyzed without a positive test.
The agency also confirmed that the remaining 27 horses on the farm were tested by Rebecca Menzies, who tested three suspicious cases on Saturday.
All the horses on the farm have tested negative, but it will be "under close surveillance and further testing will be done," the agency said.
Equine flu, like human influenza, is endemic in the UK, where racehorses are vaccinated against it. The virus is generally not considered life-threatening, but limits the competitiveness of horses.
An unvaccinated non-purebred horse was quelled in Suffolk after developing complications after the onset of equine influenza.
In another case, it was found that 10 uncultured two-year Thoroughbreds in the same district had infected the highly contagious virus.
Outbreaks of influenza in horses have occurred in nine English states since the beginning of 2019.
One case is a vaccinated non-purebred horse in a paid school in the southwest of England.
Cornelius Lysaght, correspondent of the BBC horse races
Just when people thought the light at the end of the tunnel would be brighter …
After two days of no positive test among hundreds of smears that were investigated by scientists, it was felt that resuming the race this week, maybe Wednesday, was very likely.
However, this seems to jeopardize this hope, anyway for flat races on the all-weather routes.
The Crisford operation in Newmarket is shallow, and there is no obvious link to the McCain string – surely the two stables have not had runners in the same places lately.