A leading wildlife group has called for an urgent inquiry into the escape of a large silverback gorilla from its enclosure at London Zoo.

The 29-stone male gorilla, called Kumbuka, was shot with a tranquilizer dart after escaping from its enclosure at London Zoo on Thursday evening.

The Born Free Foundation said that the incident "could have ended very differently" and said it was a "startling reminder" of the risks of keeping dangerous wild animals in captivity.

A zoo official said members of the public were "never in any danger" as the western lowland gorilla had remained in a secure keeper area.

An investigation has been launched into the "minor incident", they added.

However the Born Free Foundation has called for an inquiry and for the Zoos Expert Committee, the government advisory body, to investigate the safety and welfare of great apes in UK zoos.

Chris Draper, associate director for animal welfare and care at the foundation, said: "While we are relieved that this incident apparently ended without injury to visitors or to the gorilla, it is yet another startling reminder of the risks associated with maintaining dangerous wild animals in captivity.

"This incident could have ended very differently. We are calling for an urgent inquiry into the circumstances surrounding this escape, and into safety procedures at London Zoo."

The Born Free Foundation, which campaigns for zoos to be phased out, called on the government to increase penalties for attractions if they are found to put visitors or animals at risk.

But curator of mammals at the zoo, Malcolm Fitzpatrick, said that there were no injuries caused by the incident and Kumbuka was later seen "up and grumbling and interacting with the rest of his gorilla family".

"Our staff were able to respond quickly and Kumbuka was tranquillised and returned to his dens," he said.

He added: "At no time were any of our visitors in any danger. The gorilla did not get out of the safe space, there were only about 100 visitors."

Kumbuka, one of seven gorillas at the zoo, was reportedly agitated and charging at the enclosure's glass walls moments before the escape, according to witnesses.

As staff rushed to bring him under control, visitors were told to hide inside a bird attraction for about half an hour.