MALICIOUS hoaxers are putting lives at danger by setting off distress flares as a prank.

Coastguards spent hours searching Poole Harbour for a vessel in trouble in the early hours of Saturday morning but eventually found a group of young people they suspected of setting off the flares as a joke.

Portland coastguard watch member Philip Chappell said: "If you fire a red flare it means a life is in danger. The coastguard takes every red flare seriously.

"This was a malicious hoax and if there had been a real emergency it would have put lives in danger because we would have been in the wrong place."

The coastguard said that this was the fourth time in a week that distress flares had been fired in Poole Harbour in a non-emergency situation.

Angry Mr Chappell said: "Unhappily, we do not have powers of prosecution so we have to leave these cases to the police but often they do not do much."

Coastguards responded to the flares at 4.20am on Sunday morning after they were spotted by a nurse in the cardiac ward at Poole Hospital and by a watch officer onboard the Prince William sail training ship.

They mobilised the inshore and all weather lifeboats from Poole and two coastguard teams from Swanage.

In total more than 20 people were involved in the futile search.

A night fisherman told the officers he had seen a group of young people "up to no good".

At about 6am a mixed group of five young people were discovered walking along Beach Road on Studland.

Officers found the remains of several expended flares nearby and believed these to have been taken from a boat in Shell Bay marina.

The cold young people said they had missed the last ferry back and were stuck on the Shell Bay side.

Mr Chappell said: "We called the police and left the matter to them."

He added that similar searches had been launched on Wednesday and last Sunday nights after red flares were spotted but nothing was found.

The police said that five people were helping them with their enquiries.

Inspector Robin Hemsworth from Dorset Police said: "The marine section are dealing with this. It is being treated as a suspicious incident and it could be there was a crime such as theft from a moored boat. The police do take this seriously as it could have caused a huge amount of distress to a lot of people."

He added that such incidents waste a lot of police and coastguard time.