The mammal was found motionless on the river banks under Battersea Bridge

The mammal was found motionless on the river banks under Battersea Bridge
Stranded minke discovered by members of public near Battersea Bridge in London

A dead whale has been found in the River Thames for the third time in the past two months.

The marine mammal - believed to be a minke - was spotted swimming up and down the river in London by several members of the public on Friday.

A dog-walker later found it lying motionless in shallow water near Battersea Bridge at around 9.30pm and it was later confirmed dead when a rescue team arrived.

It comes after a humpback whale nicknamed Hessy was found dead in the Thames near Greenhithe on 8 October and a sei whale was found dead in Gravesend on 18 October.

"A whale is very unusual in the River Thames, however we have now had three in the past two months," said Martin Garside of the Port of London Authority (PLA).

"They are all different species and there is no obvious, simple cause. Hopefully we can learn about what causes it, is it just nature or is there some external reason.'

The PLA will first move the whale to a facility in east London before handing it over to experts at the Zoological Society of London (ZSL) for a necropsy.

Around 600 cetaceans (whales, dolphins and porpoises) are found stranded around the UK coastline every year, according to the ZSL.

The society's investigation of strandings in the UK over a 25 year period found that live strandings were the third highest cause of death after bycatch (unintentional capture by fishing industry) and infectious disease.