The fresh cases forced the cancellation of yesterday's meeting at Rosehill, which, ironically, was to have been the first in New South Wales that the public were allowed to attend.
The calls for mass vaccination are growing as fears increase that the highly contagious respiratory disease could spread to neighbouring Victoria.
Warwick Farm joins Sydney's Randwick - home to 700 racehorses - under lockdown.
It is understood a number of crisis meetings are planned for tomorrow, with the possibility of mass vaccination of all racehorses in Victoria on the table.
The vaccine is due to arrive in Australia on Thursday. There are 50,000 doses - enough to vaccinate 25,000 horses.
The Warwick Farm outbreak leaves Rosehill as the only virus-free training area around Sydney.
The cancellation of the meeting was taken as a precautionary measure as news of the Warwick Farm outbreak broke.
Most horses at Warwick Farm are now expected to catch the disease - following the same pattern as Randwick.
Racing NSW chief executive Peter V'Landys described it as another dark day for the state's racing.
An investigation has been launched into how the flu got to Warwick Farm. Human error is a likely cause.
Meanwhile, a discussion is likely over whether Victorian racehorses should take priority in the inoculation programme, a move which would greatly increase the chances of the lucrative spring racing carnival going ahead.
Federal Agriculture Minister Peter McGauran says the final pattern of infection would not be established for a week or two. Containment and eradication should be given a proper chance, he said.
In other news, Australia's most expensive stallion, Redoute's Choice, has contracted flu, along with several other stallions at Arrowfield Stud in NSW's Hunter Valley.
It is latest in a string of high profile studs to be affected by the disease. Arrowfield's mares first contracted the disease, and it has now spread to the stallions.
Redoute's Choice, has a stud fee of more than $A285,000.