There are growing fears this evening for the health of a 18-foot northern bottle-nosed whale which has been stranded in the River Thames since yesterday.
However, it is understood the whale is in fact injured and is in a distressed state.
Rescuers cancelled an earlier appeal for an ocean-going vessel to take the whale out to sea amid growing fears for its health, according to a spokesman for the British Divers Marine Life Rescue Group.
The vets on board were initially cautiously optimistic that it was healthy and could be released. But that has been replaced by pessimism as its condition deteriorates rapidly," according to Tony Woodley of British Divers Marine Life Rescue.
The choice facing the veterinary experts on board the barge carrying the deep-diving mammal towards the open sea was whether to release it into the estuary and hope it swam out to deep water or kill it to save it further suffering.
"It always was a trade-off between the whale 's health and the distance we could take it to deep water. It seems now the decision will have to be taken in the next couple of hours," Woodley said.
Time is crucial as the whale 's body is not designed to bear its own weight and it could begin to suffocate if kept out of the water too long.
Earlier today, rescuers successfully lifted the animal onto a barge in the hope of bringing it back out to sea. They managed to tether the injured animal close to two boats and it was towed towards the barge before a crane lifted it out of the water close to Battersea Bridge in central London.
The whale drew large crowds to witness the rare event.
Spontaneous applause broke out among onlookers as the crews of the boats manoeuvred and headed downriver while others cheered from Battersea Bridge as the whale passed beneath.
Rescuers said they were keen to move the whale away from Battersea because of fears that the rising tide would be unsafe for the team holding it there.
The barge then started to move downriver towards the Thames Estuary where the results of tests were to determine whether it was safe to release it back into deeper water.
Experts are unclear what the world's deepest-diving whale - a sociable animal that normally travels in groups - is doing on its own and in such shallow waters.
On theory is that the whale, native to the northern North Atlantic, had been following fish upstream and became disorientated.
Britain's Natural History Museum said it was the first time the species had been recorded in the Thames since its records began in 1913.
Additional reporting:Agencies.
