Sir Paul McCartney has written to Philippine President Benigno Aquino Iii urging him to speed up the transfer of a sick elephant from the Manila Zoo to a sanctuary in Thailand.

The former Beatles star has applauded the leader for intervening on behalf of animal rights groups and calling for an evaluation of ailing Mali, 39, but now he wants Aquino to revisit the elephant's condition and transfer the female to a "lush, spacious sanctuary in Thailand".

He writes, "I have great regard for governments that intervene on behalf of animals, just as yours did with the May 2012 directive ordering that Mali be evaluated and considered for transfer. That said, time is passing, and it has been more than a year since that directive was issued - yet Mali seems no closer to enjoying her well-deserved retirement at an approved sanctuary.

"I have heard from my friends at Peta that various government authorities are continuing to deny that Mali's welfare should be within their jurisdiction.

"With the stroke of a pen, you can bring an end to her suffering, and I urge you, with all my heart, to direct that Mali be given that joy now."