The Victoria Racing Club (VRC) has opened an investigation after stables at Flemington were entered illegally during the Big Day Out concert on Australia Day.The intruders, who struck in the afternoon, are believed to have let horses out of their stables to run loose.The complex of Melbourne Cup-winning trainer Mark Kavanagh is understood to be the worst affected, however, the trespassers are also believed to have entered the stables of other leading trainers.Darley's Peter Snowden and David Hay

The Victoria Racing Club (VRC) has opened an investigation after stables at Flemington were entered illegally during the Big Day Out concert on Australia Day.

The intruders, who struck in the afternoon, are believed to have let horses out of their stables to run loose.

The complex of Melbourne Cup-winning trainer Mark Kavanagh is understood to be the worst affected, however, the trespassers are also believed to have entered the stables of other leading trainers.

Darley's Peter Snowden and David Hayes are among those who train at the premier track.

VRC chief executive Dale Monteith confirmed an investigation had been launched.

"Unauthorised entry into any premises at, or surrounding, the racecourse is a very serious matter and one which the VRC will investigate in full with the assistance of police and other parties as required," Monteith said in a statement.

A leading Melbourne trainer, who did not wish to be named, confirmed that horses were released from their boxes by the intruders and let loose in the stable complex.

He added that Kavanagh's stable had been among those affected.

Along with Melbourne Cup winner Shocking, Kavanagh also trains the likes of dual Group One winner Whobegotyou and promising three-year-old Shamoline Warrior.

The VRC said that while the investigation remained ongoing they would not make any further statements.

Around 50,000 music lovers attended the Big Day Out concert at Flemington on Tuesday.