Marine experts were examining the rare northern bottle-nosed whale to find out more about the mammal whose journey this week was followed by television viewers and hordes of Londoners watching from the British capital's riverbanks.

The postmortem results will be published later this week, Tony Woodley, the director of British Divers Marine Life Rescue (BDMLR) which carried out the last-ditch rescue attempt on the distressed whale, told AFP.

In a dramatic operation on Saturday covered on live television, marine experts caught up with the whale and hoisted it onto a barge before sailing it downriver toward the North Sea.

But the health of the disorientated creature, apparently injured and exhausted, deteriorated during the operation as the barge reached the Thames Estuary, and it died after convulsions on Saturday evening, about halfway on its journey back to the sea.

The whale, dubbed "Wally" in newspapers, was removed from the barge and was being examined throughout Sunday.

Woodley said the preliminary results would be published on Wednesday or Thursday. More comprehensive results would be available a week or two later.

"Following the postmortem, the animal will be disposed of by the local authority," Woodley said, adding that health issues might mean the public would not be allowed to see the lifeless animal that brought joy and tears to those following its travails.

The marine life rescue group estimated that the rescue attempt cost about 100,000 pounds (146,000 euros, 177,000 dollars) and appealed for donors.

The Zoological Society of London said the postmortem would look for signs of damage to the whale's skin before sending blubber samples for analysis.

An internal examination would then look at the health of the whale's organs.

This was to include an examination of the "echo response" areas of the brain which may reveal if they had been damaged causing the animal to become disorientated.

Experts had warned that the whale might not have been able to cope with the stress of the noise and chaos from crowds and boats around it, as well as the pressure of its own weight on its internal organs.

They also said its lungs and eyes might have been damaged in the fresh water.

The five-to six-metre (15- to 20-foot) animal, which weighed between seven and eight tonnes, generated round-the-clock live television coverage and drew popular wonder and sympathy.

It was the first northern bottle-nose spotted in the Thames since records began in 1913. The whales, pushed close to extinction by commercial whaling until a ban was imposed 25 years ago, are normally found in deep offshore waters in the Arctic Ocean and the northern Atlantic.

Woodley defended the rescue group's intervention.

"We did the right thing for the whale," he said.

"If the whale would have been left how it was then it would have just slowly died and we don't think that was the acceptable option to take.

"We always knew that it was going to be risky. We gave it our best shot," he added.

Newspapers reflected on the whale's tragic demise and what it said about modern Britain.

The Daily Mail said "almost the entire nation" had been gripped with concern.

"Our forefathers would have harpooned the poor creature and cut it to pieces without a second thought. It is a measure of our civilisation that we (now) feel this way," the tabloid wrote.

People flocked to the Thames riverbanks on Friday to catch a glimpse of the animal, which swam more than 40 miles (60 kilometres) from the open sea.

Some experts said it may have become disorientated in the shallow water of the Thames Estuary, or may have been injured by loud sonar used by navy warships in the North Sea.

Reports said a second, larger whale was spotted in the Thames Estuary off Southend-on-Sea -- possibly an older relative.

Dolphins, seals and porpoises have all been unexpected visitors to the Thames in recent years, a testament to the recovering state of the once biologically dead tidal river.

Over the past 30 years, the Thames has improved to become one of the world's cleanest metropolitan rivers.

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