That might seem far-fetched, but no one would have expected worshippers to have been drinking hydrogen peroxide until the news broke last week. And, if there are cults around, will they wield greater social influence as they grow in strength? The Reverend Daniel Li Kam-pun, an alliance church pastor, has carried out lengthy research on sects and cults.

'People only became aware of the presence of possible cults following the recent controversy. There could be some individual groups which are engaged in strange practices in private.' For instance, the Children of God, which made headlines for its practice of promiscuity, has been driven underground but not totally wiped out, Mr Li says. 'It still has some members here; it's only that they meet in secret locations.' Over the years the Church of Zion has shunned contact with the 1,100 mainstream churches in the territory. Last year, it broke its ties with the head church in Vancouver, due to differences between Mr Leung and the leaders there.

The Reverend Luk Fai, general secretary of the Hong Kong Church Renewal Movement, an umbrella group for denominations in the territory, sees a hidden danger in what he calls 'the sect's' reclusive operations.

It spreads its teachings through its weekly service at Mongkok Stadium, and via the hundreds of tapes produced by Mr Leung himself. 'It produces no written material, so it is difficult for us to respond to or challenge what they say, and for its members to spot any problems in their teachings.' Former Zion recruits told the Post they were advised not to watch TV or read newspapers so they could stay away from Satan's influence. They were also told 1995 would see the second coming of Jesus Christ. The date has now been put off to 1999.

'Some members said the Holy Spirit had revealed itself to them,' said Gina Chui, who attended gatherings run by the group for two months under the influence of her church friends. 'And they insisted they believed in what their pastor said. I think it is dangerous that they rely so much on one person.' Ivy, a 17-year-old Form Five graduate, has been to both family gatherings and Sunday worship sessions held by the group. 'The members shun pop music too,' she said.

The Church of Zion is not the only 'marginal' Christian group in Hong Kong. The Church of Christ and the Church of God are the other two cited by Mr Luk as operating in isolation from the mainstream Christian community.

A common characteristic of the three is their emphasis on frequent gatherings. Mr Luk began to look into them a few years ago after school principals expressed concern.

They had received complaints from parents who had noticed drastic changes in their children after they joined one of the groups. 'The parents complained their children had been going to religious meetings five nights a week and were like religious fanatics,' Mr Luk said.

'How much time do the members have for other activities? They are easily detached from our society. People who had been with the groups for some time and quit afterwards said they were bombarded by strict teachings.' There were also reports of students engaging in active evangelism among their schoolmates, through controversial means. 'One principal said he had a student who took his classmate to a room, and suddenly turned off the light there to illustrate to him the darkness in hell.' At the Church of Zion, Mr Luk is more worried about a possible personality cult being built around its leader. An eloquent speaker, Mr Leung is undoubtedly charismatic.

'We are aware of his tendency to interpret the Bible as he wishes,' Mr Luk said. 'This may cause some people to think he is an authoritative figure.' That certainly seems to be the case. A Christian for several years, Ivy said she was struck when she heard Mr Leung say at a recent worship session that he knew who was sick in the audience.

'He asked them to raise their hands and come down to the podium for prayers. But if he had known who was sick, why didn't he approach them himself instead?' The stress on the Holy Spirit's activity is another characteristic of churches which do not belong to the mainstream. Mr Leung, according to Ivy, once stopped talking suddenly during an address to a congregation. 'He just stared at the ceiling and raised his hands. He said he could not talk anymore as he was being touched by the Holy Spirit.' Episodes like this may have the result of consolidating his status as a leader. Mr Luk noted: 'In any denomination, members stick together often because of either friendly relationships among them, a common understanding about life or a charismatic leader.' The son of a construction company owner, Mr Leung, now in his 30s, became involved with the Church of Zion while he was studying in Vancouver in the 1980s.

He later returned to territory to look after the local branch of the church, which is under the wing of one of Canada's most active denominations, the Glad Tidings - an independent evangelical charismatic church with 'linkages' with other churches.

In 1991, he was ordained by the Vancouver church to administer Christian ordinances here.

But after last year's split, any ties Mr Leung had with the Canadian church no longer exist.

The senior pastor of the Vancouver church, Gideon Chiu, said he had never heard of the practice of drinking hydrogen peroxide.

Basking in the admiration of his followers, Mr Leung, who lives with his wife in a flat provided by his parents, appears nevertheless as confident and exuberant as ever.

'None of our members have left despite the recent controversy,' he declared.

'And he sees no contradiction in his role as a preacher to promote a certain product.

'I have a responsibility to tell people what is good for them, just like when a missionary goes to an underdeveloped place like Africa, he or she would warn the people there not to drink unclean water.' His is certainly a close-knit organisation.

Core members lead family gatherings held from Monday to Friday at different locations across the territory. The current controversy may have little effect, if any, on their close fellowship.

There is little that the authorities, or the other churches, can do. Mr Luk said: 'Hong Kong is a free society; even heresies are seen by some as religions and tolerated.

'We can only hope people think independently and have the opportunity to communicate with others.'