Indian police shot and killed two suspected Pakistani militants on the outskirts of New Delhi early today, a day before a national holiday that has put the country on high alert.

Brij Lal, a senior police officer in Uttar Pradesh state, told reporters an anti-terrorist team chased a car carrying two men towards the capital before intercepting it in the suburb of Noida, 20km from the city.

mumbai terror attack 111208 03 He said recovered passports indicated the two dead men were Pakistani, and police were investigating if they had links to Pakistan-based Lashkar-e-Taiba (LeT), a militant group that India blames for November's attacks on Mumbai.

"They are definitely Pakistani but unless we examine the documents we cannot come to any conclusion (whether they belonged to LeT)," said Lal.

"The team asked the terrorists to surrender," he said, but they started firing at officers and in a fierce gunbattle the two men were shot in a nearby field and one officer was injured.

The militants died on the way to the hospital, he added.

Police said they found two AK-47 assault rifles, five hand grenades and detonators in the car.

The incident occurred ahead of Monday's Republic Day holiday, which is being marked amid heightened security measures after the Mumbai terror attacks.

20,000 heavily armed troops deployed

Fears that Islamist militants could disrupt the annual military parade have led to 20,000 heavily armed troops being deployed, according to Delhi police.

City police commissioner YS Dadwal earlier warned that Islamist militants could try to attack the event, which is designed to display India's role as a regional economic and military power.

"There are intelligence inputs (of possible strikes by guerrillas)," Dadwal said.

New Delhi - backed by many international governments - says LeT militants led November's carnage in Mumbai, India's financial capital, in which 10 gunmen killed 165 people.

The lone surviving attacker is in Indian custody.

India has said that given the level of sophistication of the attacks, the group must have had support from some of Pakistan's "official agencies" - a charge Islamabad has rejected.

Commissioner Dadwal said a "ground-to-air security apparatus" was in place for the Republic Day celebrations with anti-aircraft guns, snipers and helicopter gunships at the ready to thwart militant strikes.

The anniversary of Jan 26, 1950 marks India's transformation to a sovereign democratic state with a written constitution and an elected parliament after gaining independence from British rule in 1947.