BEIJING, Sept. 2 (UPI) -- Despite a panda "baby boom" in China zoos, giant pandas remain an endangered species, researchers say.

Twenty-three panda cubs have been born in zoos and research centers in the last two months, China's People's Daily reported.

"The baby boom began in early July, with 23 cubs born in captivity -- 14 at the Wolong research center, eight in Chengdu and one in Beijing," Zhang Zhihe, director of the Chengdu Research Base of Giant Panda Breeding, said.

With the births, the total number of giant pandas in captivity at zoos worldwide had topped 300, a target set by Chinese scientists in 2002, said Zhang.

"It's good news, but the number is still not big enough for the bears to be taken off the endangered list," said Zhang.

Zhang and his colleagues have worked to expand the panda population by helping the sex-shy animal breed since the Chengdu base was founded in 1989.

"The growth in the number of artificially bred pandas, however, was inevitably accompanied by a decline in the quality and genetic diversity, as many captive pandas are blood relations," said Zhang. "This will hinder the species' survival in the long run."

Zhang said 61.4 percent of captive-bred pandas are offspring of just four giant pandas -- Pan Pan and Dong Dong at the Wolong China Giant Panda Protection and Research Center, and Ha Lan and Lin Nan at the Chengdu base.

"It's hard to avoid inbreeding when so many pandas share the same blood," he said.