Crowds gathered on Ouse Bridge in York, according to North Yorkshire Police, but no one tried to save the man.

It prompted police to remind the public to not "just stand there videoing it on your mobile phone" as it gave guidance on what to do on its Facebook page.

"They [officers] were glad to help… but something they saw made them concerned," the force said.

At least two life rings were "accessible metres from the scene", police said, but it wasn't too late to save the man when police arrived.

Officers got hold of one of the life rings, which they say was 50 metres from the scene, and threw it in the man's direction.

"Our two officers kept talking to him and ensured he could keep his head above water until the fire service boat arrived and pulled him out of the river," the force added.

He was taken to hospital after the incident, which happened at around 3pm last Thursday, at the rear of the Radisson hotel.

Life rings - also known as life belts or lifebuoys - and other floatation devices are found at regular intervals along the River Ouse, police said, and along other waterways.

"Would you be a bystander or a lifesaver?" the police asked.

"It's always worth making a mental note of life ring locations along your local river in case you ever need to help someone in trouble."

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A fire service spokesperson said people should shout for help and dial 999, asking for firefighters at inland water sites or the coast guard at the beach.

"Reach with a long stick, a scarf, clothes or anything else. Crouch or lie down to avoid being pulled in," they added.

"If possible, throw a rope - you can then pull in the person. Otherwise throw something that will float - a ball, a plastic bottle or a lifebuoy. Do not jump in to try to save them."