A racehorse in Australia swam out to sea after ditching his rider on a beach in Brisbane.

Five-year-old Rebel Rover was taken to Moreton Bay for training when he spooked, causing his rider to fall off.

The loose horse then swam out to sea.

Brisbane police and the volunteer marine rescuers were called in to help.

The gelding trained by Brad Smith was two kilometres out when he was caught after two hours in the water.

He was estimated to have covered 11 kilometres.

A boat was manoeuvred close to the racehorse and a lasso was put around the top of his head so he could be pulled close to the boat to attach a rope to his bridle.

He was then dragged through the water to safety.

“Water Police were surprised to be called out on an equine adventure yesterday,” said a police spokesman on the Queenstown Police Service Facebook page.

“After disposing of his jockey, this racehorse turned seahorse was spotted doing a Phar Lap off shore.

“He was safely returned to his owner and there’s hope he becomes the new Sea Biscuit.”

Rebel Rover was “a little bit tired and sore in the muscles” following the ordeal, but was otherwise uninjured.

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Banned for bad behaviour

According to the Racing Post, when he reached dry ground he headbutted one of his support team, knocking them unconscious and putting them in hospital.

Mr Smith said the mischievous horse recently returned to racing after being banned for bad behaviour in the stalls.