Ocean Park on Monday said its baby twin pandas are now two months old and are growing up stably.

The park said the pair's eyes have fully opened and they have started developing their hearing.

It said the female now weighs 2.7 kg and her brother weighs about 2.5 kg.

Howard Chuk, head of the park's zoological operations and conservation, said staff have been sharing the job of looking after the cubs with the pandas' mother, Ying Ying.

"Although we have all the nursery facilities, including the incubator, we try to maximise the opportunities to allow Ying Ying to take care of the cubs. This benefits the behaviour, as well as the health of the cubs," Chuk said.

"But... we need to ensure Ying Ying is capable, and also we are pretty sure the babies are safe after we return or rotate the cubs back to Ying Ying."

Elke Wu, an assistant curator of zoological operations, said Ying Ying is about 80 percent recovered from giving birth.

"She's a first-time mum and she's not young anymore, so her recovery is really slow and she's very picky at her appetite," she said.

"Our whole husbandry team spends so much time looking for food that she likes, or making food into different forms that she will be willing to take in, and we literally just feed it into her mouth sometimes."

Wu said it is still difficult to tell the twins apart but they have different characteristics, with the female having messy fur and the male having rounder dark circles around his eyes.