A man was detained Monday night in relation to the death of a panda last Thursday in Jinan City of east China's Shandong Province, municipal police said Tuesday.

Workers, hired by the 48-year-old suspect surnamed Yang, were disinfecting a former air-raid shelter when toxic gas leaked through an air-pipe to the nearby panda house of Jinan Zoo, poisoning the bear to death, said a spokesman for the municipal police.

Yang had leased the former air-raid shelter to grow mushrooms.

"The shelter was legally leased and we were not aware of the air-pipe, which was not included in the facility's design paper," said a spokeswoman for the local civil air defense office of Jinan's Tianqiao district, which owns the shelter.

The air-pipe was drilled in 1995 to help cooling the panda house in summer, according to a statement from the zoo.

"It's an extraordinary case and looks like an accident." said Chang Jiwen, a scholar with the Institute of Law under the Chinese Academy of Social Sciences.

But the people who drilled the air-pipe should be held accountable and the zoo should take management responsibility, Chang added.

The female panda Quan Quan, a star at Jinan Zoo and a "heroic mother," had given birth to seven cubs. It was found poisoned at around 7 p.m. and died in a local hospital after three hours of treatment failed.

Quan Quan arrived at Jinan zoo three years ago. Aged 21, the panda was the equivalent of a woman more than 70 years old.

Giant pandas are among the most endangered species in the world, with only a few thousand living in the wild, mountainous areas of southwest China.