Local authorities announced the birth of two giant panda cubs at Ocean Park Hong Kong to the world's oldest first-time panda mother.

The female and male cubs were born after being conceived naturally by mother Ying Ying and father Le Le in March, the government in Hong Kong said in a statement. They were the first panda twins to be born in Hong Kong.

"This is a very critical period for the health of the newborn giant panda cubs," the statement said.

Experts from the zoo and the China Conservation and Research Centre for the Giant Panda (CCRCGP) have been monitoring the condition of Ying Ying and her cubs around the clock, it added.

Ying Ying turned 19 on Friday, making her the world's oldest first-time panda mother, Ocean Park said.

"This birth is a true rarity, especially considering Ying Ying is the oldest giant panda on record to have successfully given birth for the first time," said Ocean Park Corporation Chairperson Paulo Pong in a statement.

According to the zoo, the newborn male weighed 112 grams (3.95 ounces), while the female, who appeared slightly weaker, weighed 122 grams (4.3 ounces).

Naturally conceived panda cubs are a rarity in zoos because giant pandas rarely breed in captivity and females are only fertile for a few days every year.

Ying Ying and Le Le were given to Hong Kong by Beijing in 2007.

The endangered pandas are found in the wild mainly in the south-western Chinese province of Sichuan. China has a long history of lending pandas to foreign countries, a practice often referred to as "panda diplomacy."