Expert triathletes on a sea training exercise sparked an emergency rescue operation when passers by thought they were drowning.

The swimmers were holding onto a bouy waiting for the rest of their group to catch up when a coastguard crew tried to rescue them.

The redfaced athletes, members of Alnwick District Triathlon Club, explained they were in the middle of training for an event in Scotland next week - and were in no danger.

The club hosts regular training sessions off the coast of Craster, Northumberland, but this time walkers spotted the group leader - who has swum in the North Sea for 20 years - clinging to a bouy and phoned 999.

Now the club has agreed to inform the coastguard during future training sessions to avoid further embarrassment or confusion.

Club secretary Frances Anderson said: "I think somebody got a little bit over anxious, as it was a bit of a shock when the lifeboat turned up. "I saw it from the shore where I was watching the training.

"It is good to know they are that quick to respond if we really did have a problem.

"But we had experienced swimmers in an organised group, so there was no problem."

Atheletes from the Alnwick club compete all over the UK.

She said: "I can understand why some people thought there might be a problem.

"They must have seen the guys clinging to the bouy and thought what on earth is going on? "But every training session is organised and safe.

"We will have to make sure we keep the coastguard informed in future."

Triathletes combine running, swimming, and cycling over a variety of distances, and participants have to train for long periods of time.

A spokesman for Humber Coastguard said: "We have received assurances from the organisers they will let us know before they go out training in the future."