WASHINGTON (AFP) - He didn't blow out any candles, but the Washington National Zoo's giant panda Bei Bei appeared to enjoy celebrating his fourth birthday on Thursday (Aug 22), his last before being shipped back to China.

The roly-poly black-and-white bear, one of the zoo's star attractions, was treated to a colorful "panda-friendly" frozen cake made of fruit, carrots, sweet potatoes, sugar cane and bamboo, the zoo announced.

The birthday celebration for Bei Bei could be viewed live thanks to the zoo's "Panda Cam," which broadcasts scenes of the four-year-old and his siblings and parents from their enclosure round-the-clock.

Bei Bei will soon be returned to China, under terms of the agreement that brought him to the US zoo on loan.

The same fate awaits his sister Bao Bao and their brother Tai Shan.

Their parents Mei Xiang and Tian Tian will remain in Washington at least until next year.

Under the loan agreement, the zoo pays China US$500,000 (S$690,000) a year to support conservation efforts there, and any panda cubs born at the zoo may stay until age four, according to the Smithsonian website.

Zoo officials said they did not yet have an exact date for Bei Bei's move, but said it would take place "in the coming months."

Transporting such a large animal thousands of kilometres - Bei Bei weighs around 118kg - is no simple matter, they added.

It involves working with other federal agencies, researching travel logistics, coordinating with colleagues in China and preparing Bei Bei for the move.

The young panda's name, which translates as "Precious," was announced during a 2015 zoo visit by then-First Lady Michelle Obama and Peng Liyuan, the wife of Chinese leader Xi Jinping.