An injured whale stranded in a sea loch on the west coast of Lewis died yesterday.

The northern bottle-nosed adult whale was beached in Loch Roag on Monday. Fish farm workers spotted the 40ft mammal and raised the alarm.

Volunteers from the British Divers Marine Life Rescue (BDMLR) attended and identified the seven-tonne whale, but soon afterwards it managed to refloat itself and was seen swimming around the loch.

However, blood was seen around its dorsal fin. A vet confirmed it had been injured and was in distress, which might require it to be put down. It disappeared only to be found dead at the head of the loch at around 10.30am.

Rescue volunteers said the whale appeared to have died from natural causes but scientists from the Scottish Agricultural College will carry out a post-mortem examination on the carcass.

Tony Woodley, of BDMLR, said volunteers had noticed the whale was underweight and in poor condition.

"The whale restranded in a very inaccessible area for our volunteers. This was an animal that was quite thin and ill and underweight "It may have had problems navigating when it turned back and became disorientated. Clearly nature has taken its path with this one. It was in a sick state," he said.

Police warned the public to stay away from the area as there was a risk of water contamination.

They said that the relevant authorities were informed and had begun to tend to the carcass.