At least 21 dolphins have died in a river in Cornwall after the biggest mass stranding in almost thirty years.

A major rescue operation was launched after a pod of around 15 striped dolphins swam up the Percuil River near Falmouth, before they were beached in Porth Creek.

It is understood that the distress calls from those dolphins attracted many more into the river and this morning a rescue effort was led by British Divers Marine Life Rescue (BDMLR) with the coastguard and local wildlife trusts.

The rescuers managed to save seven of the stranded animals and the last two were taken out to deep water in stretchers attached to boats.

The coastguard said by the time the boats left a pod of up to 60 dolphins were following them.

Tony Woodley, national spokesman for BDMLR, said: "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."

Volunteers have been checking the river to ensure there are no more beached or distressed animals.

A spokeswoman for the RNLI said: "We are coming to the end of the rescue operation now, the last two are being taken out to sea.

"There are a lot of dolphins still in and around the river but they have managed to stop any going up towards the creek."

The scene this morning was described as "carnage" by the first lifeboat crew to arrive.

Helmsman Dave Nicoll said many of the dolphins were already dead, with others struggling in the shallow waters or on the river edge.

He said: "It's a horrible scene of carnage with bodies everywhere.

"We think the pod were attracted by the cries for help from those that are stuck in the creek."

The RNLI said 20 of the dolphins were already dead and one was put down by a vet.

The carcasses of the dead animals have been removed from the creek and taken away for post-mortem examination.

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