Indian Prime Minister Manmohan Singh condemned the attack as a "terrorist act" and appealed for calm after the assault on the temple-mosque compound in Ayodyha, one of the most bitterly disputed religious sites in the world.

But the main Hindu nationalist party -- which rose to prominence after the Babri Mosque at the site was demolished in 1992 by Hindu right-wingers -- quickly called for nationwide protests across India on Wednesday.

Police said one of the attackers may have been a "human bomb" laden with explosives as the group launched its assault on the compound around 9:15 am (0345 GMT), sparking a two-hour shootout with security forces.

"In the ensuing gunbattle, six of them were killed," said Jyoti Sinha, director general of the Central Reserve Police Force. "One person, who possibly was a human bomb ... was blown to pieces."

Three policemen were wounded. Police seized four gas masks, several rocket launchers seven AK-47 assault rifles, 15 hand-grenades, Sinha said.

"This has been a successful operation as the police officials managed to have everything in control just within two hours," said Uttar Pradesh state home secretary Alok Sinha said.

Television footage showed body parts strewn around the complex, where the Babri Mosque was razed by Hindu zealots in December 1992, triggering bloody riots that left 2,000 dead across India.

Indian intelligence agencies have often said the disputed Ayodhya site is a prime target for Islamic rebels fighting in northern Kashmir, and the city was put under a security siege in 2002 over reports of a possible attack.

But the largest militant group in Kashmir, Hizbul Mujahedin, denied any role in Tuesday's assault and pointed the blame at Hindu hardliners.

"The incident seems to be the handiwork of Hindu extremists to trigger anti-Muslim riots in India," a spokesman of the group told the Current News Service in Kashmir.

Federal home ministry secretary Vinod Duggal said no group had claimed responsibility for the attack, but linked the action to militants.

"It's obvious that it is a militant group. Which one has done it we'll find out soon," he said.

India's federal security cabinet reviewed the attack and put security forces on "sharp lookout" across the country to guard against possible violent sectarian protests, especially at religious places.

"The attackers wanted to create a dangerous situation," Indian Home Minister Shivraj Patil said.

Hindu activists say the Ayodyha mosque was built by Muslim rulers in the 16th century after they destroyed a temple marking the birthplace of the Hindu deity Ram.

They have been arguing for a Hindu temple to be built over the site of the demolished mosque on the sprawling 80-acre (26-hectare) compound, and the dispute is pending before the courts.