An American visitor had a part of her thumb bit off by a panda cub as she was feeding it bamboo at a reserve in southwest China.

Identified only as Lisa, 50, she was listed in the Wolong Giant Panda Protection and Research Center as a volunteer.

Xinhua reports that Lisa had been wearing gloves and was giving the panda bamboo when "suddenly, the panda bit into her thumb."

"When she cried out, the cub became excited and gripped more tightly," it said. "Lisa finally managed to wrench herself free."

An estimated 20 percent of her thumb had been bitten off.

The Wolong Giant Panda Protection and Research Center has been known to take in volunteers since 2004 for assignments that could be as short as one day to more than a month.

Volunteers will be able to prepare food, feed pandas and clear the enclosure with the aid of professional supervision.

Volunteers from America, Japan, Switzerland, France and Spain numbering to more than 1,200 had already come to work in the center.