Holidaymakers have been warned against swimming in the sea after two killer whales were spotted hunting prey off the coast of Abu Dhabi in the United Arab Emirates.

The orcas have never been spotted so close to the shoreline before, according to local fishermen.

Footage shot by the fishermen shows the whales circling a dugong - a seal-like sea mammal - in shallow waters near the mainland on Tuesday May 9.

Their distinct black and white colouring and long dorsal fins pick them out as one of the ocean's most feared predators.

As the orcas circle the fishermen's boat, the dugong's brownish body can be seen just below the surface of the crystal-clear water.

One of the orcas was a massive 40 feet (12 metres) long, according to one of the fishermen, while the other one appeared to be much smaller, possibly a young calf being taught to hunt by its mother, with the pair filmed leaping out of the sea and splashing back down.

In the footage, one of the fishermen can be heard saying in English: 'I can't believe it.'

Local media reported that hotels have closed their beaches to swimmers on the advice of Abu Dhabi's Department of Culture and Tourism until the orcas have moved on.

Ahmed Afifi, 40, the fisherman who shot the footage, said: 'It is normal they like to play with their food, sometimes they even kill big whales to eat their tongue or liver and leave the rest.'

He also said that it was the first time that killer whales have been spotted so close to the coast, calling the sighting 'very rare and unbelievable'.

Ahmed said that killer whales had once been spotted about 120 kilometres (75 miles) off the coast, but never so near to dry land.

He said that a researcher from Zayed University who he named as Ada Natoli said that these two killer whales were last spotted off the coast of Sri Lanka.

The fisherman, who said that he quit the banking industry to start his fishing organisation called Just Fishing in 2018 and now organises fishing outings all over the world, added: 'Our business specialises in sports fishing charters with five boats. Our vision is to see Abu Dhabi become one of the world's top sports fishing destinations.

'Abu Dhabi's waters are very rich in kingfish, groupers, Golden trevally, and cobia (black runner) due to the decision to ban net fishing and cages.'