A beluga whale first spotted in the River Thames on Tuesday was seen swimming toward London on Wednesday morning, raising fears the "very lost" mammal's life could be in danger.

Nicknamed "Benny" by British media, the beluga whale was seen feeding off Gravesend in Kent, slightly west of where it was first seen on the Essex side of the river near Coalhouse Fort.

The whale may have taken a wrong turn after entering the North Sea and ended up 1,600 kilometers south of its normal range, possibly due to storms last week, experts said. It was seen swimming strongly, raising hopes that it would find its way back out of the river to the open sea.

Following the new sighting on Wednesday, the British Divers Marine Life Rescue (known as BDMLR) said it was sending teams back to the scene.

Lucy Babey, head of science and conservation for ORCA, a charity which studies whales, dolphins and porpoises, is working in conjunction with BDMLR.

She told the BBC teams will monitor its behavior to see what condition it is in and if action needs to be taken. Ships in the river were being urged to keep clear.

"This animal is thousands of miles away from where it should be. It's slightly concerning. These animals can navigate in shallow coastal water so hopefully it will swim away," she said

She said any noise in the water could impair its sophisticated sonar navigation system.

Teri Charlton, of the BDLMR, said: "The best thing for it is for it to get out to the sea." She added that the animal had been swimming strongly and had been feeding.

There are occasional reports of beluga whales off the British coast, though very rarely this far south. The charity Whale and Dolphin Conservation said it believed that the beluga sighting was the first in the Thames.

Whale and Dolphin Conservation spokesman Danny Groves said: "This is a High Arctic species thousands of miles from where it should be in Greenland, Svalbard or the Barents Sea. They are usually associated close to the ice.

"He or she is obviously very lost and quite possibly in trouble."

Beluga whales were last spotted in the UK three years ago off the coast of Northumberland and Northern Ireland, but sightings were "extremely rare", according to the BDLMR.

In 2006, a 5 meter northern bottle-nosed whale died after becoming stranded in the Thames.