Wednesday brought double happiness to Pairi Daiza zoo in Brugelette, Belgium, as giant panda twins Bao Di and Bao Mei celebrated their fourth birthday and the zoo's owner received the original of a reply letter from President Xi Jinping.

Eric Domb, founder and president of Pairi Daiza, located about 60 kilometers south of Brussels, said he was thrilled to receive the original letter signed by Xi, which was delivered by Chinese Ambassador to Belgium Cao Zhongming. In June, Domb had received a copy of Xi's reply letter.

On March 30, 2014, Xi and his wife, Peng Liyuan, attended the opening ceremony of the zoo's giant panda garden together with King Philippe and Queen Mathilde of Belgium. During the visit, Xi had planted a magnolia tree.

A few months ago, Domb wrote a letter to Xi recalling the visit and including pictures of the blooming magnolia tree in the zoo's Chinese garden. He was not sure if he would receive a reply letter from a busy head of state.

Domb, who has visited China more than 20 times, said on Wednesday that he was really touched by the kind gesture of President Xi and was very happy to receive the original letter.

"China's efforts to protect the environment should be known to more people. The giant panda was once an endangered species. China acted with unimaginable will to save the animals," Domb said. He added that China's efforts "tell us what needs to be done in the area of animal and environment protection".

Pairi Daiza had received its first pair of giant pandas, Xing Hui and Hao Hao, in February 2014, a month before Xi's visit. Two years after their arrival, the bear pair had a male cub, Tian Bao, on June 2, 2016. He was the first giant panda born in Belgium.

On Aug 8, 2019, the panda parents had twins — male Bao Di and female Bao Mei. Domb called it "the birth of the dragon and the phoenix", mythological creatures that are considered auspicious in Chinese culture.