India draped itself in a heavy security curtain and boosted anti-insurgency operations on Tuesday as the country celebrated its 60th Republic Day amid hijack warnings and stepped up violence in the disputed Kashmir region.

Cities, railways and airports in many parts of the country stepped up vigilance while troops were a visible presence on the streets of the capital ahead of an annual parade to showcase India's military strength and culture.

This year's Republic Day, which usually sees attacks by militants in the insurgency-hit northeast and Kashmir, comes at a time when tension between India and Pakistan is running high over border skirmishes, and a spike in separatist violence.

Troops in Kashmir said they foiled a major attack by separatists with the recovery of a large cache of arms and explosives, which they claimed were to be used on January 26.

Some 42,000 police have been deployed to guard Mumbai alone, which witnessed a militant rampage on some of its most memorable landmarks in 2008 that killed 166 people and revived tension between India and Pakistan.

"There is no specific alert from intelligence agencies but we are on high alert anyway," D. Sivanandan, the Mumbai Police Commissioner, told Reuters.

"There will be policemen patrolling all over the city, including iconic structures, high rises, parade grounds, etc."

This year, South Korean President Lee Myung-bak is the chief guest at the parade, in a nod to growing bilateral business ties, to watch the tanks and armoured cars roll by and fighter jets roar over the heads of thousands of people expected to attend.

Last week, the Interior Ministry recommended extra security checks such as more frisking and air marshals on flights after intelligence on a possible hijack attempt

The Air Force was also put on the highest alert after agencies warned of a possible air attack by Lashkar-e-Taiba, the Pakistan-based group New Delhi blames for Mumbai.

Troops intensified patrols and searches in states riddled by separatist and Maoist insurgencies.

Rebels repeated an annual call to boycott the celebrations, which mark the founding of the Indian republic after independence from the Britain in 1947.

Some violence was reported on Monday. Police said Maoist guerrillas, who say they are waging war against the Indian government on behalf of the poor, blew up a control room of a telecoms firm in Chhattisgarh state.

Cars stayed off the road and mining activities were hit in parts of the mineral-rich state of Orissa as Maoists attempted a statewide shutdown and economic blockade, police said.

In the northeast, home to several separatist revolts, thousands of troops stepped up counter-insurgency operations and killed several rebels. Authorities have stopped trains in the region running after dark as a precaution.

Witnesses said police and paramilitary in full battle gear patrolled several busy streets in Srinagar, the summer capital of Jammu and Kashmir, frisking bus passengers and pedestrians.-Reuters