London  At least 21 dolphins have died after becoming stranded in a river creek in Cornwall, south-west Britain, in what rescuers Monday described as a "scene of carnage."

Coastguards said the drama began early Monday when a first pod of dolphins swam up the Percuil River near the port of Falmouth and got stuck in the creek.

As they died, their distress signals lured other dolphins to the river.

Teams of conservationists, divers, coastguards and local government officials were helping Monday to send the surviving dolphins back to sea.

"It's a horrible scene of carnage with bodies everywhere," said Dave Nicoll from the Falmouth lifeboat association.

Tony Woodley, the national spokesman for British Divers Marine Life Rescue, said it was the biggest mass stranding of marine life for 27 years.

"We haven't seen a stranding anywhere near this scale since 1981 when pilot whales were beached on the east coast. This is extremely rare," said Woodley.

"Logistically a rescue like this is a minefield, it is very difficult to manage. You have to get all the dolphins together, if one or two leave the river system they will just come back to rejoin the main social group," he said. (dpa)