A young minke whale that became stranded in the Thames has been put down.
A vet from London Zoo euthanised the animal after it became "very distressed" and was seen trapped against the riverbank near Teddington in the southwest of the capital.
The whale will be taken away by experts from the UK Cetacean Strandings Investigation Programme.
They will carry out the equivalent of a post-mortem examination to establish where it came from and what may have happened.
"We can now confirm that the minke whale at Teddington Lock has been humanely put to sleep after the animal restranded on the nearby embankment," said British Divers Marine Life Rescue.
"Medics used inflatable pontoons to prevent the animal from slipping back into the river, which allowed the veterinary team from the Zoological Society of London to further assess the animal and end its suffering."
Rescuers had previously said it was unlikely the mammal, which was between 3m (10ft) and 4m (13m) long, would survive and make it back to the sea.
The animal was first spotted at Richmond Lock and Weir at around 7pm on Sunday.
The Port of London Authority (PLA) told Sky News the whale was freed at 1am on Monday after a joint operation by the London Fire Brigade, a Royal National Lifeboat Institute (RNLI) crew, and the British Divers Marine Life Rescue.
It was later spotted upstream towards Teddington, where another set of locks and a weir stops the tide from passing further up London’s waterway.
RNLI volunteers were monitoring the whale, which was thought to be underweight and may have had some injuries on its pectoral fins.
A PLA spokesman earlier said the whale was towed along the river to Isleworth but managed to break free and swam away.
A Chiswick RNLI spokeswoman said: "Chiswick’s RNLI crew were tasked by London Coastguard at 8pm on Sunday May 9 and worked with the fire rescue service, police and British Divers Marine Life Rescue to try to free the whale.
"Together they managed to free it and were taking it to a deeper part of the river when it swam away.
"The whale was displaying concerning behaviours and experts in attendance were concerned that it may be unwell."
Minke whales are the smallest of the great whales, growing to about 10 metres.
They can usually be found throughout the northern Atlantic and Pacific oceans.