Photo shows a crowd of injured dogs, with their mouths being tied up by bandages, lying on the rooftop of a teaching building in Xi’an Medical University. [Photo: cnwest.com]

Xi'an Medical School apologized Monday for mistreating the dogs it used in clinical experiments, after photos and videos of infuriated animal lovers across the country.

In a widely-shared video, posted by an unidentified Internet user, a dozen dogs were surrounded by medical towels and packages, and their mouths were tied up with cloth, two were bleeding and twitching, the rest catatonic.

Coverage of the footage by China Central Television and other media triggered online outcry over the weekend, with tens of thousands of people taking to social media to vent their anger.

"How could students and teachers at a medical school be so contemptuous of animals' lives?" one Weibo user named "Naomiko" said.

The college in northwest China issued an official response on its website on Sunday. It admitted to animal cruelty, while stressing that its experiments were in line with regulations.

On Monday, school spokeswoman Xiong Dongmei said that all animal experiments had been temporarily suspended.

"These dogs have now been put down. They were about to die when the video was shot. But it's true we did not give them enough care," Xiong said.

The school would learn from the incident and correct all wrongdoings, she added.

The school could not be reached for further comment.

Dogs used in clinical experiments are usually given drugs to ensure they die a humane death, local media reported, citing an anonymous teacher from the school.

In China, special regulations stipulate that clinical experiments on animals must feature care throughout, and any pain inflicted on the animals must be kept to the bare minimum, according to the circumstances.