An outbreak of equine flu has led to the postponement of horse racing in Britain until February 13, at the earliest, the British Horseracing Authority (BHA) has announced.

All fixtures on Thursday were called off the BHA after three vaccinated horses tested positive for the disease.

Trainer Donald McCain has confirmed the horses came from his Cheshire stables.

Horses from the infected yard raced on Wednesday, potentially exposing a significant number of horses.

“This precautionary approach is intended to ensure we put the health of the horse population and control of the virus first, and avoid any unnecessary risk that might come from returning to racing too quickly,” said a BHA statement.

“We appreciate the impact that this may have on the sport commercially, but disease control in order to mitigate the risk of further disruption to the sport - and safeguard the health and welfare of our horses - must be a priority.”

The meetings at Chelmsford, Doncaster, Ffos Las and Huntingdon on Thursday were cancelled. Racing had been due to take place at Bangor, Kempton Park, Newcastle and Southwell on Friday.

On Saturday, Lingfield, Newbury, Uttoxeter, Warwick and Wolverhampton were on the schedule, with Exeter and Southwell hosting events on Sunday.

This announcement also means the Monday races at Catterick, Hereford and Wolverhampton will not go ahead, nor will the fixtures on Tuesday at Ayr, Lingfield and Newcastle.

The statement added: “The BHA’s veterinary team has today been in contact with more than 50 trainers and veterinarians to allow it to make an informed assessment of the risk of equine influenza spreading.

“While no further positive tests have been received, at least three more days are required before it will be possible to make a decision about whether it is safe to resume racing.

“The disease can take up to three days before symptoms are visible, meaning it will take until Sunday at the earliest before the BHA can gather all the information required.

“This approach will allow samples to be collected and assessed by the Animal Health Trust in order that a fully informed decision can be made on Monday. This may then allow declarations to take place on Tuesday in time for racing on Wednesday.”