India's charismatic Hindu ascetics have always been looked up to for their spiritual help and have claimed powers to perform miracles, but now, they're being closely watched - for all the wrong reasons.

Last week, one of these 'godmen' was arrested for running a vast sex racket from his temple, while another was shown in a TV sting expose allegedly having sex with an actress.

Yet godmen still command millions of followers in this deeply religious country - despite frequent media reports of their worldly weaknesses that have seen them being involved in all sorts of criminal activities, including rape, murder and extortion.

There are those who scoff at these purveyors of spirituality and laugh at the gullibility of their followers, and rationalists who have challenged the godmen to perform 'miracles' in front of them.

"There is a new awareness developing in this country and I am very, very happy about it - that is why more and more godmen are being exposed," said Sanal Edamaruku.

The president of the Indian Rationalist Association had once challenged a mystic to demonstrate his powers by killing him using only magic on a TV show. Accepting the challenge, the mystic chanted mantras and performed a ritual. When nothing happened, he said Mr Edamakuru had to be under the protection of a powerful god - to which the rationalist responded that he was an atheist.

In the latest scandal, Delhi police arrested Shiv Murat Dwivedi, a 39-year-old man with flowing black hair and beard, for allegedly running a sex racket from his temple.

According to police, he had more than 100 girls working for him, including college students, air hostesses and society women.

Dwivedi, who worked as a security guard at a five-star hotel and at a massage parlour before taking to religion, was said to have amassed more than 600 million rupees (US$13 million) over a period of 10 years.

Even as Dwivedi's followers were recovering from the shock of his arrest, Swami Nithyananda, 45, who has an ashram, or spiritual centre, outside IT hub Bangalore, was allegedly filmed having sex with an actress in a TV sting operation.

Though a spokesman for the Swami, or holy man, denied the charge and dubbed it as a "conspiracy", angry mobs attacked his ashram and his properties in Karnataka state.

"For us it is a very, very astonishing matter that the Swami has been indulging in these sex and criminal activities. He should be punished and this ashram should be shut down permanently," a protester was quoted as saying.

Of all the godmen, perhaps the most controversial has been Chandraswami, who is facing a string of criminal charges, including cheating and violations of the Foreign Exchange Regulation Act.

According to the prosecutors, the 60-year-old, who had the ears of two former prime ministers - P.V. Narasimha Rao and Chandra Shekhar - and several leading politicians, is also suspected of having a role in funding the 1991 assassination of former prime minister Rajiv Gandhi.

Mr Gandhi was assassinated by a woman suicide bomber of Sri Lanka's Tamil Tiger rebels.

But critics acknowledge that it would be wrong to tar all spiritual leaders with the same brush. They cite instances of Sathya Sai Baba as well as Mata Amritanandamayi, popularly known as the 'hugging mother', who have used donations from their worldwide followers to set up universities and super speciality hospitals, where the poor are given treatment at subsidised or no cost.

The latter had donated 10 billion rupees to Sri Lanka in the wake of the 2004 tsunami devastation to build houses for the victims, and also helped rebuild the houses of those affected by the tidal waves in her Kerala state.