Sea World staff are celebrating the pitter-patter of polar bear paws after 16-year-old Liya gave birth to twins.

The second-time mother is caring for her “rat-sized” cubs inside a maternity den, away from the theme parks other two polar bears, twin brothers Hudson and Nelson.

The 15-centimetre-long cubs were born on Wednesday and each weighs approximately 600 grams.

Director of marine service Trevor Long said both adult males spent time with Liya but they suspect Hudson fathered the twins.

“Due to the time, it’s an eight month gestation, she repeatedly mated with Hudson,” Mr Long said.

It is the second successful breeding at the Gold Coast park with Liya giving birth to Henry in 2013.

Henry was moved to Canada two years ago and now lives at a research sanctuary.

Keepers are using infrared cameras and microphones to monitor the mother and cubs around the clock.

The new-borns sleep for about an hour at a time, and are awake for approximately 90 minutes.

“In that hour-and-a-half we can watch them suckling with mum and watch them explore and start to move around,” Mr Long said.

He said while first-time mothers usually raise one cub, he is confident Liya is experienced enough to not choose one cub over another.

“Most of the time, experienced mums will have two, remember they can have anywhere up to four,” he said.

“Liya has been equally attentive to both cubs at the moment.”

Polar bears are born blind and it takes up to three weeks for them to open their eyes.

The cubs are expected to leave the den in July and they could go on public display in August.

The have not yet been named.