Minister for Agriculture, Tony Burke, says it is expected the horses can now be released.

The final test result was on blood samples taken previously from all the horses, including the horse which provided a positive result for equine influenza on its fifth mandatory quarantine nasal swab test.

"All the tests for equine influenza at the quarantine station have now concluded and the advice is that all horses from Eastern Creek are free of equine influenza," Mr Burke said.

"While those involved in quarantine must always remain vigilant, those who love the races can now get on with enjoying the Spring Racing Carnival.

"Since the horse flu outbreak last year we made it clear we require close monitoring and strict enforcement of quarantine procedures – and that is unchanged."