The National Zoo does not rule out the possibility to let a pair of giant pandas, Xing Xing and Liang Liang to mate for the second time after their cub, Nuan Nuan returns to China, before the end of the year.

Its Zoological and Veterinary director Dr Mat Naim Ramli said however, it would depend on the desire of the giant pandas to mate during their fertility period between April and May.

"Since the pair will only go through the mating process once a year, from April to May, we need to monitor their movements before placing them in one cage.

"If successful and their second cub is born, the cub will go through the same process as Nuan Nuan which will be sent back to China after it turns two," he told reporters at the pair's 11th birthday celebration at the Giant Panda Conservation Centre (GPCC) here Wednesday.

Also present were Chinese Ambassador to Malaysia Dr Huang Huikang, National Zoo president Datuk Zaharin Md Arif and its deputy president Rosly @ Rahmat Ahmat Lana.

Dr Mat Naim said the GPCC created history when a cub was born within a year after the arrival of the pair from Chengdu in 2014.

"Other giant pandas in other zoos and conservation centres outside China may take up to five years to give birth," he said.

He said the centre was trying to train Nuan Nuan to adapt to the special cage, where she would be placed during a flight back to China, since last month.

Dr Mat Naim said Xing Xing currently weighed at 130kg while Liang Liang 108kg and Nuan Nuan 78kg.

The pair of giant pandas had been loaned to Malaysia by China under an international conservation cooperation programme as part of the efforts to strengthen bilateral relations.

-- BERNAMA