A man has been banned from one of China’s leading panda centres for life after throwing unspecified “objects” into an enclosure.

A notice from the Chengdu Research Base of Giant Panda Breeding did not identify the objects, but said feeding pandas may cause them harm.

It added that the panda appeared to be unharmed, and identified the visitor as a 53-year-old man with the family name Gao.

“In view of Gao’s uncivilised visit and his behaviour that may cause harm to giant pandas, he is prohibited from entering the panda base for life,” the notice said.

The Chengdu centre has previously imposed lifetime bans for feeding pandas.

A man who fed bamboo shoots to panda cubs in an activity area and a woman who gave them peanuts were barred for life last August.

Other visitors have been banned for one or five years for offences such as throwing water at a panda or banging hard on enclosure windows, according to state media reports.

The giant panda has become a national symbol for China, loaned to zoos around the world.

President Xi Jinping, on a visit to the US last year, called them “envoys of friendship between the Chinese and American peoples”.

The breeding centre in Chengdu, the capital of Sichuan province, is a popular tourist destination.

A total of 34 pandas were born last year at two bases in Sichuan, including the one in Chengdu. Some made a special appearance recently as part of this month’s Lunar New Year festivities.

“The national treasure has strict dietary standards,” the Chengdu Research Base wrote in its notice, requesting visitors to be civilised and lead by example.