Buddhist followers attempting a religious practice that involved the live release of some 500 turtles were stopped at Peking University on Wednesday afternoon.

Faculty and staff prevented the group from releasing the turtles into a lake located near the campus’ Sackler Museum of Archeology.

The five women and a man, who identified themselves as Buddhist followers, said they had “done the same thing last year” and that the live release is “just a religious practice”.

The group had brought a number of mesh bags containing a large number of Brazilian slider turtles, some described to be the size of two adult male palms. Brazilian slider turtles are not indigenous to China, and have been described in Chinese reports as “ecology killers”.

Under orders from the university, the group eventually left the campus, and brought their turtles with them.

Global Times reports that Peking University has said the live release of animals on its campus is banned, and will seek punishments for those who violate the rule.

Live release, or fangsheng (放生), is a Buddhist practice whereby live animals are purchased from markets and set free into the natural environment. However, the practice is causing wide-scale damage to Chinese ecosystems as new species are introduced into environments where they don’t fit into the local food chain.

Practiced once every two months, the live release of fish into Daming Lake in Jinan, Shandong has resulted in an ecological disaster, with upwards of 50 kilograms of dead fish collected from the lake each day. Despite the good intentions, the Chinese public hasn’t looked fondly upon live releases. A woman who released venomous snakes into a Shenzhen Park in 2014 was met with an online backlash.

Although not affiliated with the religious practice, the live release of fireflies at special events in China has also become a cause of concern for scientists.