WATCH: Infant minke whale stranded in London’s Thames

Fears were growing in London on Monday for the fate of an infant whale that was rescued from the banks of the River Thames, only to swim upstream instead of out to sea.

The young minke whale, measuring three to four metres (10-13 feet), was first spotted in southwest London on Sunday and was washed ashore at a set of gates controlling water flow.

Hundreds of onlookers gathered to watch the stranded whale as it was hosed down and attended to by a vet, with concerns it could be injured and appeared to be underweight.

There were cheers at the scene when, at around 9:00pm (20:00 GMT), crews from the Royal National Lifeboat Institute (RNLI) arrived to rescue the beached mammal.

It was not until 1:00am that teams from the RNLI, the London Fire Brigade and the British Divers Marine Life Rescue service managed to free it with the help of an inflatable cushion.

Despite the success of the rescue attempt, the whale managed to swim away from the cushion that was guiding it to safety, the BBC reported.

A juvenile Minke whale swims under a bridge at Teddington in southwest London after it swam up the river Thames on May 10, 2021. (Photo by Glyn KIRK / AFP)

While it was initially seen at around 10:00 am heading east towards where the Thames opens into the North Sea, the whale was later spotted returning upstream.

A spokeswoman for the RNLI said the whale managed to get away while rescuers were “taking it to a deeper part of the river”.

“The whale was displaying concerning behaviours and experts in attendance were concerned that it may be unwell,” she added.

London Fire Brigade station commander Glen Nicolaides called the event “a very rare and unusual incident”.

“Our crews were on stand-by while a marine biologist and vet assessed the condition of the whale. The mammal was removed for further assessment by marine specialists,” he added.

Jake Manketo, 20, a resident of southwest London where the whale became washed up, said everyone in the crowds that gathered was “just hoping they get it out”.

“We couldn’t believe our eyes when we first saw the poor fella — it’s not every day something like this happens,” he added.

Minke whales are the smallest of the world’s great whales and typically grow to a length of 10 metres in adulthood.

They can usually be found throughout the northern Atlantic and Pacific oceans but have been spotted as far north as the Arctic and as far south as the Equator.

In January 2006, a northern bottlenose whale became stuck in the Thames, sparking huge media interest. It died as it was being ferried back out to sea.