Korea-born twin pandas, Rui Bao and Hui Bao, enjoy a bamboo cake for their third birthday in Yongin, Gyeonggi Province, Tuesday. Joint Press Corps

A birthday party was thrown Tuesday for twin pandas at an amusement park in Yongin, just south of Seoul, with the Korea-born animals set to return to China in the near future.

Zookeepers and around 30 fans gathered to mark the third birthday of Rui Bao and Hui Bao, who are scheduled to return to China later in the year.

China has ownership of all pandas, including those born outside of China, and sends them to other countries only on a lease basis. Pandas, which are an endangered species, must return to their home country before turning four, when their reproductive maturity begins.

To mark the third and last birthday party here before their return, zookeepers prepared a massive cake made of bamboo — pandas' favorite snack — and gifted them a custom-made wooden bench designed for the pair to sit together.