Police found the remains of a man they believe either deliberately or unwittingly triggered the blast that launched the assault, said Jyoti Sinha, chief of the Central Reserve Police Force at the Ram Janmbhoomi shrine in the city of Ayodhya. Sinha's paramilitary force guards much of the site, which is claimed by both Hindus and Muslims.

In 1992, Hindu nationalists demolished a 16th-century Muslim mosque on the sprawling 32-hectare complex, sparking religious riots that killed more than 2,000 people.

Hindu leaders claim the mosque was built by Mogul rulers on the site of a sacred Hindu temple. They believe it is the birthplace of Ram, the highest god in the Hindu pantheon, but Muslims say there is no proof of that claim. The dispute is still working its way through India's courts.

"There were six militants. Five of them were killed by the security forces. Another body, torn into pieces, was found near the scene of the blast. He was perhaps used as a human bomb,'' Sinha said. The assault lasted nearly two hours and three security forces suffered injuries, he added.

The blast tore a massive hole in the iron railings surrounding the shrine, allowing the attackers to get within 50 metres of the temple's inner sanctum before security personnel gunned them down, a paramilitary soldier said.

"They even threw a hand grenade toward the idol of god Rama, but it didn't explode,'' said Manvendra Singh. "One of them also had an AK-47 assault rifle and another attacker had a carbine.''

The attackers used two vehicles in the assault -- a jeep loaded with explosives that blew up part of the fence, and a taxi in which they travelled to the complex posing as tourists, said Alok Sinha, the home secretary of Uttar Pradesh state, where Ayodhya is located.

Police arrested the taxi driver, a Muslim identified as Syed Rehan, who later said he had never met the attackers before, police officer Surendera Prasad told reporters in Ayodhya, 550 kilometres east of the capital, New Delhi.

Security officials in New Delhi said intelligence reports had indicated that militant groups were planning to attack religious sites.

Prime Minister Manmohan Singh strongly condemned the attack and said the government would deal firmly with any terrorists.

Ayodhya is guarded at all times by thousands of police and paramilitary soldiers, and the site has multiple barricades where visitors are frisked before being allowed in. Security is so tight that even pens, pencils, lighters and matchboxes are prohibited.

No militant group claimed responsibility for the attack, and national Home Secretary V.K. Duggal refused to single out a particular group.

But Hindu nationalists quickly blamed Pakistan-backed militants from the Indian-controlled portion of Kashmir, and said the incident proved India's recent peace overtures with Islamabad were a failure. India and Pakistan are pursuing peace after years of acrimony.

It was "an attack by jihad terrorists,'' said a spokesman for the Hindu nationalist group Rashtriya Swayamsevak Sangh. "There should be protests against this across the country, peacefully,'' spokesman Ram Madhav said.

The group is the ideological fountainhead of all Hindu organizations in India, including the main opposition Bharatiya Janata Party, which called for a nationwide strike on Wednesday to protest the assault.

The violence Tuesday was the first major attack on a Hindu temple site since a 2002 assault on the Akshardham temple in western Gujarat state, which left 32 people dead, including two attackers. That attack was blamed on the Pakistan-based Lashkar-e Tayyaba group -- one of more than a dozen guerrilla groups fighting for Kashmir's independence or its merger with mostly Muslim Pakistan.