Swimmers were piled onto a jetski and evacuated from the water at Manly Beach (above) on Thursday morning

Lifeguards piled swimmers onto a jetski to help them flee the water after a shark alarm sparked panic at one of Sydney’s most popular beaches.

Beachgoers at Manly Beach on Thursday morning were rushed from the water onto a crowded jetski after the alarm was raised.

It came at the same time a group of dedicated swimmers were seen completing their daily lap from Manly to Shelly Beach – about 1.5km.

A witness said the rescue was a ‘desperate’ attempt by lifeguards to prevent an attack.

Swimmers were piled onto a jetski and evacuated from the water at Manly Beach (above) on Thursday morning

Swimmers were piled onto a jetski and evacuated from the water at Manly Beach (above) on Thursday morning

Swimmers were piled onto a jetski and evacuated from the water at Manly Beach (above) on Thursday morning

‘I heard the shark alarm go off, I looked up and I saw the jetski hanging around the swimmers,’ they told News LTD.

‘It looked like he was driving up to all the swimmers and talking to them, they all started piling onto the jetski.

‘There were six or so people that climbed up onto the jetski and he started to drive them back to shore.’

They said some swimmers chose to ignore the warning and stayed in the water but were cleared out shortly after.

‘The lifeguard was driving right next to them and yelling and whistling,’ the witness said. 

It comes just weeks after a dolphin’s body was washed up on Shelly Beach with numerous shark bites.

The dolphin was spotted in the shallows at about 6.30am in late January after locals reportedly saw three bull sharks circling it further offshore.