SHANGHAI, China (AP) -- The birth of twin pandas at a research center brought the number of the endangered species born in captivity this year in China to a record 25, a news report said Tuesday.

The number of births so far this year is up from at least 19 for the research program in 2005, the official Xinhua News Agency said.

The twins, both weighing about 5 1/2 ounces, were born Monday at the Wolong Giant Panda Protection and Research Center in the southwestern province of Sichuan. The as-yet-unnamed cubs were the first for their 8-year-old mother Youyou, the report said.

The bears are the sixth set of twins born to captive pandas this year -- a sign of the growing success of China's extensive breeding program, which relies heavily on artificial insemination, Chinese researchers say.

"We've pretty much resolved the problems of infertility among pandas," the center's director Zhang Zhihe was quoted as telling Chinese media.

China, the only wild home of the giant panda, has raised millions of dollars in funding for research into the notoriously slow-reproducing animals by renting them to zoos around the world.

That has produced growing successes in breeding pandas, mainly at Wolong and another center in the nearby city of Chengdu, as well as studies into the lives of wild pandas.

Last month, the government announced the birth of four sets of panda twins, and another pair was born last week, although one of the cubs was accidentally crushed by its mother.

China has more than 180 pandas living in captivity and possibly up to 3,000 in the wild, according to a recent study.

(Associated Press)