6ft swordfish found on UK riverbank 1,500 miles from the Mediterranean.

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Washed up: This swordfish was found on Severn Beach, on the mouth of the River Severn

A massive swordfish was found washed up on a British tidal riverbank - an extremely rare sight in the UK.

Beachcombers saw the majestic fish - which measured 6ft in length including its bill - struggling in shallow waters but could not save it.

Experts believe the fish travelled more than 1,500 miles to Severn Beach on the mouth of the River Severn in South Gloucestershire - all the way from the Mediterranean.

Nicola Hills, 39, from Severn Beach, found the swordfish with her husband Gary.

She said: "We were walking the dog and we saw this thing thrashing about in the water.

"The first thing I thought was 'what the hell is that?' I thought it was a shark or a dolphin or something."

She added: "It looked very tired and the water was going out pretty fast. It was already in trouble. I sent my husband down there to try to save it.

"We spent about an hour and a half or two hours trying to get it to float but we were too late."

The bakery manager, who regularly walks her dogs along the sea wall in Severn Beach, added: "It was amazing. To see him pull that out of the water was crazy.

"It was a very big fish. It was at least the length of me.

"It literally took two men to carry it out of the sea. Unless you had a wheelbarrow you weren't getting it very far.

"I've never ever seen anything like it."

Swordfish, which often grow to more than three metres in length, are typically found in tropical waters where temperatures are around 18-22 degrees Celsius, such as in the Indian and Pacific oceans.

They move to warmer waters in the winter and cooler waters in the summer but it is "very rare" for them to be spotted near Britain, where temperatures drop to 6 degrees Celsius or lower.

Records show there have been less than 10 sightings of swordfish in British waters over the last 10 years.

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Something fishy: Experts believe the swordfish travelled all the way from the Med

Only three have ever washed up dead on the seashore, predominately off North Wales, and could have been carried hundreds of miles on the current. But this is the first to be found in a river.

Charles Tyler, an expert in environmental biology at University of Exeter, Devon, said: "This swordfish is most likely to have come up from the Mediterranean.

"It is likely that the swordfish was chasing something like mackerel or salmon, or that it became caught in a net.

"The swordfish is one of the most amazing fish species.

"They have a system whereby they can elevate their body temperature and are very charismatic.

"It is rare for them to be reported in these waters and it is a real treat to see one - it's just a shame it died."