Three panda keepers bitten by two bears were reprimanded after an online outcry over their rough handling of the normally docile animals at the Chengdu Research Base of Giant Panda Breeding in Sichuan province, according to a base official.

The keepers - two men and a woman who graduated from college last year - had tried to prevent the two pandas from leaving their den because a routine examination was scheduled for the next day. They promised to perform better after the reprimand from senior managers at the base, the official said.

On July 12, a netizen posted a video clip showing the three keepers repeatedly throwing the two pandas back into their den, and pushing and pulling the animals to prevent them from leaving with two other bears.

Many online viewers were astonished to see the pandas being thrown to the ground in their den and criticized the keepers.

The video clip was taken from a live broadcast - a joint effort of the base and Sichuan Radio and Television Station. The station installed video cameras in several parts of the base to provide 24-hour live broadcasts of the bears, said the official, who asked not to be identified.

The netizen did not post the portion of video showing the three keepers being bitten.

At around 6 pm on July 12, the keepers fed four pandas in the den. To prepare for the examination, the keepers needed to take away the two bears that would not be examined, leaving only the two that would be checked.

But the two pandas to be examined also wanted to leave the den and bit the keepers, who were trying to stop them.

To prevent the bears from hurting them again and escaping, the three keepers reacted improperly, the official said.

Guo Jingpeng, one of the keepers, showed two holes in his middle finger when he was interviewed by reporters in Chengdu on Thursday. The wounds were from panda bites, he said.

Wild by nature, captive pandas can occasionally be fierce, said Zhou Mengqi, a photographer in Chengdu who has documented pandas since 1989.

Zhou said that long ago the animals were carnivores. Gradually, as their environment changed, so did their diet. Now they eat only bamboo.

In June 1992, when Zhou was photographing a panda eating bamboo outside its den at the Chengdu base, the animal chased him away and bit his trousers, he said.