The mink whale that became stranded in the Thames near Teddington Lock on Sunday evening (May 9) is not likely to survive and may have to be euthanised, experts have said.

Despite a rescue attempt succeeding in getting the whale freed from the lock, the prognosis reportedly looks bleak for its survival and return to the sea.

Vets were expected to carry out health checks on the whale Monday afternoon to assess its state after it swam far inland in the Thames away from its natural habitat in the sea.

Dan Jarvis, welfare development and field support officer at the British Divers Marine Life Rescue service, said the veterinarian will carry out a health assessment on the whale.

He told the PA news agency: "From the assessment that we gave last night we already know the animal’s in poor nutritional condition which doesn’t have a good prognosis, so in all likelihood the animal would be put to sleep to prevent further suffering in this case."

Ocean Strandings Investigation Programme (CSIP) which carries out post-mortem examinations.

He said the Port of London Authority (PLA) would likely need to intervene to help make arrangements for the removal of the whale.

Crowds gathered at Richmond Lock and Weir after the whale, believed to be a Minke and between three to four metres long, became stuck on the lock’s boat rollers at around 7pm on Sunday.

A spokesman for the PLA, which owns and operates the lock, previously said: "At around 7pm on Sunday, a small whale, approximately 3-4m long, believed to be a Minke whale, became stranded at Richmond Lock and Weir.

"PLA staff have attempted to assist the whale with water along with British Divers Marine Life Rescue."