BENNY the Beluga whale was spotted for a third day in the River Thames as marine experts said it could stay for months.

The Beluga, which is normally used to swimming in Arctic waters, was first spotted on Tuesday morning between Gravesend and Tilbury in the River Thames.

British Divers Marine Life Rescue Director Geoff Hammock and Thames region coordinator Sam Lipman used a Rigid Inflatable Boat (RIB) to get close to the Beluga whale.

Mr Hammock said: "It is as well as can be expected.

"We think it is feeding."

He added: “We think that if there was not any food it would have been looking for food.

"It keeps coming back to the same point."

But Ms Lipman said the whale could stay in the Thames “for weeks or months if he or she is happy feeding.”

She added: "We are looking at body condition and behaviour.

"We are just going on what we can observe.

"It looks like it could be a sub-adult, it has grey tinges.

"There have only been about 20 reports in British waters so it is a really rare occurrence."

The whale, which is believed to be up to three metres long, was spotted at 10:30am on the Kent side on Thursday morning.

Richard Sabin, a whale expert from London's Natural History Museum, previously said: "Belugas eat a wide variety of prey and this will increase this animal's survival chances.”

"It's good news he appears to be feeding well because he will stand a greater chance of returning north to his normal habitat if he can stay strong."

A spokesman for ORCA added: “The experts on the ground are monitoring closely and if the situation changes plans are in place to respond quickly and effectively.”