A team of international vets using tranquiliser darts, flatbreads and the soothing lyrics of Frank Sinatra conducted a medical examination Friday on Pakistan's only Asian elephant, ahead of his planned move to Cambodia.

The plight of Kaavan, an overweight, 35-year-old bull elephant has drawn international condemnation and highlighted the woeful state of Islamabad's zoo, where conditions are so bad a judge in May ordered all the animals to be moved.

Following the high court ruling, Austria-based animal welfare and rescue group Four Paws International were enlisted to help move Kaavan -- whose case was boosted by the singer and activist Cher -- as well as two brown bears and three wolves.

A transport crate must be built and the elephant habituated to it before he can be flown to a Cambodian wildlife sanctuary in a "jumbo" jet -- probably a giant Antonov An-225 airlift cargo craft.

But first, experts must know how Kaavan has fared since his last examination in 2016, so on Friday they sedated him to get up close.

Armed with a tub filled with bananas and flatbreads, Four Paws veterinarian Amir Khalil coaxed the elephant into his emptied-out concrete bathing pond while head vet Frank Goeritz used a tranquiliser pistol to fire three large darts into the animal's shoulder.

Unaccustomed to close human contact, the elephant grew a little agitated, prompting Khalil to sing Sinatra's classic melody "My Way", which appeared to calm the pachyderm as he chomped on chapatis.

Once the tranquilisers kicked in, Khalil and Goeritz measured Kaavan's hefty frame and girth, took blood samples and inserted a microchip in his left ear.

"He is in good general condition... but he is totally obese, he weighs way too much and his feet are terrible," said Goeritz, pointing to the elephant's cracked and malformed toenails that will need medical attention. 

'Bored' elephant 

Goeritz said Kaavan has been eating up to 200 kilogrammes of sugar cane each day and deprived of intellectual stimuli, resulting in "stereotypic" behaviour where he swooshes his head and trunk from side to side for hours on end.

"He is bored. He needs definitely physical and mental challenges," said Goeritz, who has previously worked with elephants across Africa.

Outrage over Kaavan, gifted by Sri Lanka in 1985, went global a few years ago after California vet Samar Khan saw him chained in his enclosure during a visit to Islamabad.

She launched an online petition that eventually caught the attention of American pop icon Cher.

"I was horrified to find he had been chained for 28 years," Khan told AFP.

Kaavan's mate Saheli, who arrived also from Sri Lanka in 1990, died of gangrene in 2012. It is hoped Kavaan might eventually be able to re-partner once he is moved to Cambodia.

Tireless efforts by a team of local animal advocates resulted in May's court ruling, under which Kaavan was supposed to be moved within 30 days, though the deadline has been extended.

Only a few animals remain but attempts by local zoo staff -- many of whom have never been given animal care training -- to move some of them have been disastrous.

Two lions and an ostrich died during or soon after they were relocated. Zookeepers tried to scare one lion out of its pen by setting piles of hay on fire.