For Hans de Kraker, a trip to India to see Sathya Sai Baba, a self-proclaimed god with a following of up to 25 million devotees, was a spiritual quest. But he said the pilgrimage ended when the 73-year-old guru tried to force him to perform oral sex.

Mr de Kraker, who now lives in Sydney, has gone public to alert devotees to a sex scandal that is threatening to undo Sai Baba, by far the most popular of India's new-age gurus.

"It is devastating to realise the man you see as a spiritual master is simply conning people for his own sexual gratification," Mr de Kraker, 32, said. "After a while you notice that the people chosen for private interviews tend to be good-looking young males."

Mr de Kraker, who first visited Sai Baba's ashram in 1992, said the guru would regularly rub oil on his genitals, claiming it was a religious cleansing, and eventually tried to force him to perform oral sex. He was kicked out of the ashram after alerting senior officials in 1996.

Mr de Kraker's story is not an isolated one, and a growing list of alleged victims is threatening to engulf the Sai Baba organisation, which has an estimated worth of $6billion. Droves have left after allegations of paedophilia and the rape of male followers.

Sai Baba's main ashram in Puttaparthi, India, is the largest in the world and can sleep up to 10,000 people. That number of people regularly turn out to "darshan", a twice-daily ritual in which Sai Baba walks among devotees choosing people for private interviews.

It is in these private interviews that many of the alleged assaults against males between the ages of seven and 30 take place. Former devotees said the interviews usually involved family groups, but when young males were involved they were ushered into a second room, behind what has come to be known as the "curtain of shame".

The organisation has been shut down in Sweden after revelations that Conny Larson, now a film star in that country, was molested by Sai Baba. The FBI is looking into similar allegations made by American children and there are investigations into the sect in France and Germany.

Both UNESCO and Flinders University in South Australia and Flinders University in South Australia pulled out of a conference organised by Sai Baba in September because of concerns about the guru's sexual conduct. In Australia, the sect is estimated to have up to 5000 followers. It runs schools in northern NSW and Western Australia, and has meditation centres across the country.

Now Australian victims are preparing documents to present to federal authorities about the guru's activities.

Terry Gallagher, a property developer from Kiama, in New South Wales, regularly visited Sai Baba in the early 1990s and spent three years as the coordinator of the group in Australia. He left the group in the mid '90s after boys in Indian schools run by Sai Baba complained to him of sexual abuse.

"Spiritually it is devastating. I'm concerned because of both the sexual abuse of young boys, and the spiritual fraud Sai Baba perpetrates," Mr Gallagher said.

Sri Ramanathan, a former Sri Lankan judge and head of the Sai Baba Organisation in Australia and Papua New Guinea, refuses to warn families taking children to Puttaparthi about the allegations.

"All god men have these kind of allegations levelled at them, why should I warn people of these allegations, they are just allegations?" he said. "He is a holy man. I know that (these allegations) cannot be proved."

Raphael Aron, the director of Cult Counselling, said: "These organisations are run by one individual and there are never any complaint mechanisms. When these sorts of allegations come up, the usual response is that it is some kind of test of faith and the whole thing is denied."

Several former devotees who spoke to The Sunday Age said they had been thrown out of Sai Baba's ashrams when they questioned leaders about the charges.

The sexual exploits of the guru were exposed 30 years ago by Tal Brooke, a former high-ranked devotee who now runs a cult-watch group in the US. "It appears that now he is out of control. The problem is that people have such faith that these allegations would kill them spiritually," he said from his home in California.