The removal order was based on allegations that the bear's Mexican owner imported it illegally with false documents.

Using polar bears in a tropical circus sounds like a sick joke, but these animals aren't laughing

Activist Debbie Leahy

Officials declined to say whether they had any plans for the circus's other performing bears.

Animal rights campaigners argue that a tropical island is no place for bears accustomed to sub-zero temperatures.

But the circus denies any wrongdoing.

The bear is now headed for a specially designed enclosure at a zoo in Maryland.

Star attraction

Alaska was removed as a result of DNA tests to check her identity after discrepancies in her documents were noticed.

It took two hours to sedate the 360-kilogramme (800 pound) female bear and take it away in a refrigerated truck.

They are the law and they mistreated the animal. This is so you see who is mistreating the bears

Circus owner

The bear was one of seven performing tricks during a ten-minute act as a main attraction at the Suarez Brothers Circus.

The animals tower on their hind legs and take turns to slide down a ramp, reportedly panting heavily through the routine.

One animal activist from the Humane Society said a video she filmed last August showed the caged bears drooling and swaying in heat of 113 F (45 C), without water.

Other campaigners described them as thin, lethargic, filthy and diseased, and forced to live in cramped conditions despite the heat.

"Using polar bears in a tropical circus sounds like a sick joke, but these animals aren't laughing", said Debbie Leahy of People for the Ethical Treatment of Animals.

Circus owner Raul Suarez said he would appeal against the seizure of the bear, and criticised the way the authorities handled her.

"They are the law and they mistreated the animal. This is so you see who is mistreating the bears," he said.

Animal cruelty charges had been brought against Mr Suarez in the US territory, but he was acquitted on 28 February.