By Alex Kleiderman BBC News

Hundreds of onlookers turned up to see the rare sight

The rare sight of a whale in the Thames in central London brought crowds - and the world's media - out to the banks of the river.

Hundreds of onlookers watched in wonder as the northern bottle-nosed whale, an endangered species, swam in the river on Friday.

"I've never seen a whale before and never thought I'd see one on the Thames," said David Bracegirdle.

The art tutor, who spent several hours taking pictures, said it was "impressive" but he was concerned for the animal's safety.

The crowds continued to gather as the 16-18ft (5m) long whale swam past the landmark of the Houses of Parliament to Albert Bridge in Chelsea, followed by rescuers in boats.

Cheers

As news spread, more than 300 people lined the banks of the Thames to get their glimpse of the mammal, the first such sighting since records began nearly a century ago.

As the whale surfaced every four or five minutes, spouting water from its blowhole, cameras clicked and cheers went up.

The crowds built up as news of the unusual sight spread

Accountant Shameen Khan was on a shopping trip on New Bond Street when she got a call from a friend telling her a whale - her favourite animal - had been spotted in the river near to his Chelsea home.

"I thought I should go and see it but I then got in a taxi and was heading somewhere else," she said.

"I then thought, 'You just live your life. You've got to come and see that whale'."

I have never seen a whale before. It's not something that happens too often in London. Louise Keen Rescuers ready for whale Whale in pictures

Louise Keen took an extended lunch break to follow the whale's journey from central London on her bike, stopping at the bridges along the way to get a better view.

The medical school administrator said: "I heard about it on the news when it was at Westminster Bridge and thought I'd go to see if I could head it off.

"It nearly got beached at Albert Bridge and a guy jumped in the water and had to push it back out.

"He got people to clap and stamp on the bridge to encourage it."

Ms Keen added: "I have never seen a whale before. It's not something that happens too often in London."

'Particularly bizarre'

Builders working on plush riverside apartments by Chelsea Embankment downed tools and peered over scaffolding to get a birds eye view of the event.

Builders stopped work as the whale passed by

Carpenter Richard Howart was down at the riverside.

"I thought I'd come down and have a look," he said. "I've seen it come up, popping up for air.

"I've seen whales in sea life exhibits in Florida but never anything like this."

But even those who have experienced the animal in the wild could not help admiring the Thames whale.

Vincent Petersen said he found the situation "particularly bizarre".

"In November I was out in New Zealand to do some whale watching among other things.