Indian police have detained the country's biggest yoga star and stormed his camp where thousands of followers were taking part in a demonstration and hunger strike against corruption.

Police fired tear gas and used batons in a raid in the early hours on a vast tent in central New Delhi where Swami Baba Ramdev, a televised yoga guru, had begun a "fast unto death" on Saturday.

"We had given permission for only 5,000 people to attend his yoga camp but 50,000 turned up. We had not given any permission for a public agitation," police spokesman Rajan Bhagat said.

Local reports said Mr Ramdev would be flown out of Delhi and returned to his residence in the town of Haridwar in the foothills of the Himalayas, where he runs a vast empire of yoga, television shows and healing centres.

Television pictures showed followers attempt to shield the guru as police moved in on Sunday morning.

The Press Trust of India said 30 people were injured, but the figure could not be independently confirmed.

Mr Ramdev had piled pressure on the scandal-hit government over corruption after vowing to go on a hunger strike to protest against so-called "black money" - cash from bribes or other illegal transactions in overseas accounts.

He had demanded the government accept all of his demands to tackle the problem, including introducing the death penalty for corrupt officials and withdrawing large denomination bank notes used in illicit cash deals.

The administration of prime minister Manmohan Singh had earlier attempted to talk him out of the fast, nervous that his campaign would become a major challenge to his authority with public anger about graft running high.

Mr Ramdev is popular among millions of Indians who watch his daily televised yoga sessions and he has strong backing from the main opposition party, the Bharatiya Janata Party (BJP), and other right-wing Hindu nationalist groups.

A succession of ministers was sent by Mr Singh to meet Mr Ramdev as he arrived in the capital on Wednesday, including top political fixer Pranab Mukherjee, the country's finance minister.

But the bearded guru - who says he can cure homosexuality, cancer and AIDS through yoga and other alternative therapies - had vowed to continue the protest despite signs the two sides had worked out a face-saving solution.

Commentators initially questioned the government's willingness to appease Mr Ramdev, saying it highlighted the administration's weakness.

"Why is the government so afraid of Ramdev?" asked the tabloid Mail Today in a front-page headline on Saturday.

But the hardline approach in the early hours of Sunday is likely to lead to fierce criticism.

"It is a sad day for democracy when police swoop after midnight on unsuspecting people," said social activist Swami Agnivesh, who was closely involved in another fast against corruption in April.

"A lathi [baton] charge and the use of tear gas on a crowd of people is completely uncalled for," he told the CNN-IBN news channel.

Anupama Jha, the director in India for anti-corruption lobby group Transparency International, said the police raid "shows how rattled the government was by the campaign".

- AFP