Marine conservationists fear the animal, described as "worryingly thin", could starve if it stays in the waterway that flows through Paris.

The whale was spotted on Wednesday and fire crews used a drone to monitor it swimming through a stretch of the river between the French capital and the city of Rouen in Normandy.

Normandy Eure region fire service officer, Patrick Herot, said the "impressive" sea creature seemed "calm", adding it doesn't seem stressed and is "surfacing regularly".

However, the whale barely moved on Thursday and on Friday is said to have been wandering in a 25-mile stretch of water between two sets of locks north-west of Paris.

It swam away from boats hoping to guide it in the direction of the river mouth, between the sea ports of Le Havre and Honfleur.

Removing the beluga from the water is not possible as it could put the animal at risk, Ms Essemlali said.

But it is unlikely to survive long in fresh water - with underwater noise from ships and boats causing confusion for whales.

Conservation group Sea Shepherd France warned the animal urgently needs food and help to guide it home.

"It is condemned to die if it stays in the Seine," group president Lamya Essemlali, told TF1.

"The challenge will now be to help feed it and try to accompany it towards the ocean."

Drone footage captured the animal's silhouette just below the waterline before it rose to the surface to breathe.

It is unclear why the animal left Arctic waters.

Belugas' are famed for their pale skin and bulbous foreheads. They are also known to be sociable animals which habitually live, hunt and migrate together in pods.

In May last year a minke whale had to be euthanised after it became stranded in the River Thames.

A dead whale was pulled from the waterway near Gravesend, Kent, in October 2019 - less than five miles away from where a humpback whale was struck by a boat days earlier.