South Korea's largest Buddhist order is in disarray after a secret video was broadcast of monks smoking, drinking and gambling in a luxury hotel room.

Just before Koreans' national holiday celebrating the birth of Buddha, South Korean TV aired shots of monks belonging to the Jogye order playing poker with stakes of more than £543,000.

Jaseung, the head of the order which has 10 million followers, around a fifth of the population in South Korea, public apologised for the incident, vowing "self-repentance". Six leaders of the order have also resigned.

But many see the case as only the tip of the iceberg of a wider problem in the country: corrupt practices in religious groups. In response, some activists have called on the government to introduce a "tax on religion".

The footage came to light when Seongho, who had previously been expelled from the order for defaming its leader, submitted it as evidence after reporting the incident to prosecutors. He claimed that he found a USB drive containing the footage on the floor of his temple and that the tape had been recorded with a hidden camera in the hotel room.

Gambling is illegal in South Korea, except for at licensed casinos and horse racing tracks. "Buddhist rules say don't steal. Look at what they did, they abused money from Buddhists for gambling," Seongho said.

Jaseung has since apologised to all of the country's Buddhists.

"We deeply apologise for the behaviour of several monks in our order," he said in a statement. "The monks who have caused public concern are currently being investigated and will be punished according to Buddhist regulations as soon as the truth is verified by the prosecution."

The scandal also excited attention on Twitter, with some posts calling for reforms within the sect.

"It can be good news. Please, Jogye order, cut out the rotten part before it gets worse and take this opportunity to be reborn," one tweet said.

Chung Yoon-sun, secretary-general of the Buddhist Solidarity for Reform, said political conflicts between monks have become commonplace in Korean society.

"It's just like politics," he told the Korea Times. "In society, if there's a conflict of interest between two groups, they make a deal or they fight. There have been cases in the past in which monks physically assaulted each other. Especially during the election two years ago, the problem was most severe. This incident also might have something to do with the upcoming election in the autumn."

Shot of video showing South Korean monks smoking, drinking and playing poker in a hotel room (Screengrab)