LONDON — A beluga whale was spotted in the River Thames outside the British capital on Tuesday, officials said. It was reported to be feeding near a number of barges.

Beluga whales are identified by distinctive white markings and are typically found farther north, the Whale and Dolphin Conservation group said.

"Beluga whales inhabit cold, arctic waters off Greenland, Svalbard and in the Barents Sea," the group said in a statement. "There have only been around 20 sightings of beluga whales off the U.K. coast previously, but these have occurred off Northumberland, Northern Ireland and Scotland."

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The whale that was spotted Tuesday was "obviously very lost and quite possibly in trouble," the Whale and Dolphin Conservation said.

The unusual sighting happened in the Gravesend area about 30 miles east of London. It was first spotted by Dave Andrews, an ecologist and ornithologist, BBC News reports.

Can't believe I'm writing this, no joke - BELUGA in the Thames off Coalhouse Fort @RareBirdAlertUK pic.twitter.com/6VtrJ1PVc6 — Dave Andrews (@iPterodroma) September 25, 2018

The RSPCA animal welfare group said that it was "working with other agencies to monitor the situation" and sent researchers to the scene. It said it is ready to provide help to the whale if asked to do so by other agencies.

Tanya Ferry, environment manager at the Port of London Authority, said it was unclear what the whale could eat.

"If they are eating things like jellyfish, we don't tend to have a great deal of jellyfish in the Thames, but we do have quite a lot of plastic bags, which could be quite an issue," she said, BBC News reported.

"We're hoping if we give it enough space and keep an eye on it, it will find its own way out of the Thames to an environment that's more appropriate for it.

The River Thames, one of the longest rivers in England, runs through several major cities and towns, including London, Oxford and Windsor.

TV news helicopters filmed the white whale from the air as officials asked the public not to get too close to the animal.