A Siberian tiger has given birth to two cubs in northwest China zoo, bringing hope for the endangered species, zoo officials said Friday.

The tiger gave birth to the cubs two weeks ago, said zoo worker Yang Weiguo in Xining capital of China's Qinghai Province

"It was natural breeding, a real miracle in the plateau region," said Yang, who looks after the tigers at the Qinghai-Tibet Plateau Safari Park in Xining.

He said the tiger and her cubs were all in good condition. "The cubs have not yet opened their eyes, but have a very good appetite."

Zoo workers were unable to approach the cubs for a closer look under their mother's watchful eyes, Yang said.

Zoo workers fed the mother tiger mutton, live chickens, milk and eggs to ensure adequate lactation, he said.

The mother tiger is three and a half years old and was born at a zoo in Ningbo, east China's Zhejiang Province. The cubs' father was born at the Beijing Zoo in 2000.

Park manager Liu Chuanhui said the 300-hectare safari park provides a wild habitat for the animals.

He said the cubs would not be put on public display before they were a month old. "But we have installed camera lens in the tigers' pen, and visitors can watch live video of the mother and the cubs."

The Siberian tiger is a subspecies of tiger which once roamed western, central Asia and eastern Russia. It is estimated that the number of wild Siberian tigers is now between 350 and 450 worldwide.

China has around 20 wild Siberian tigers, among which 10 to 14 are in northeastern Heilongjiang Province and eight to 10 are in its neighboring Jilin Province.

China established a breeding base for the Siberian tigers in Heilongjiang in 1986 and the number of tigers in captivity has increased from eight to more than 800 so far.