Two more pairs of twin panda cubs have been born in the China Wolong Giant Panda Protection and Research Center, based in southwestern Sichuan Province, bringing the total number of new born panda cubs on the Chinese mainland to 10 so far this year.

The newborns include three female cubs but the gender of the fourth one remained unknown as it wal still in the arms of its mother, sources with the center said.

Giant panda Xi Mei gave birth to the twin cubs on Saturday at the Wolong center, two days after Qian Qian, who gave birth to another pair of twin cubs Thursday, Li Desheng, deputy director of the Wolong center, told Xinhua on Sunday.

"The two mothers and their babies are all well," said Li.

A pair of twin giant pandas gave birth to twin cubs in a panda research center based in Chengdu, capital of Sichuan Province, on August 6 and August 7 respectively.

China is embracing a good "harvest' of newborn panda cubs recently. The Wolong center welcomed the birth of a 218-gram cub male on Monday, the heaviest cub born in the history of China's artificial reproduction program which began in the 1960s. China's first panda cub for this year was born in the center in July.

Studies from the State Forestry Administration show there are over 180 giant pandas living captivity on the Chinese mainland.

Experts had previously estimated there were 1,590 giant pandas living in the wild in China. But Chinese and British scientists announced in June that there could be as many as 3,000 after a survey using a new method to profile DNA from giant panda feces.