New Delhi  - India honoured security personnel killed during the Mumbai terrorist attacks as the nation celebrated its 60th Republic Day Monday with a military parade in New Delhi amid heavy security.

The event began on a sombre note with President Pratibha Patil conferring India's highest gallantry awards, the Ashok Chakra medals posthumously to six policemen and commandos for bravery during the November 26 attacks.

India has blamed the Pakistan-based Lashkar-e-Taiba militant group for carrying out the attacks that killed 173 people including 26 foreign nationals.

In all, 11 Ashok Chakra medals were presented to the widows and a mother of policemen killed in Mumbai, New Delhi and the conflictive northern Jammu and Kashmir state.

It was the first time such a large number of gallantry medals have been awarded on a single occasion. India faced its worst terrorist attacks during 2008 that claimed more than 400 lives and left more than 1,000 injured.

In a nationwide address, President Patil urged the international community to take "decisive and united action" against the "epicentre of terrorism" in the region.

"The concerted and well-planned attacks in Mumbai stand out as an example of a ruthless operation undertaken to damage the confidence of India," she said.

"Countries must own up to their responsibilities," Patil said in an apparent veiled reference to Pakistan.

Over the past weeks, India has repeatedly asked the Pakistani government to take action against elements involved in the Mumbai carnage and extradite the suspects for trial in India.

After the presentation of the awards, India's military might and diverse cultural heritage were showcased in a parade on the Rajpath avenue which links the Presidential Palace and the India Gate.

Patil took the salute as the contingents from the armed forces, police and paramilitary forces marched through the thoroughfare. Kazakhstan President Nursultan Nazarbayev was the chief guest at the function.

The defence forces showcased their latest military armament and put up a show of airpower as the frontline Sukhoi-30 combat jets zipped across Delhi skies.

Colourful tableaux depicting the diverse culture of India's states and performances by folk dancers and schoolchildren followed the marching troops.

India celebrates January 26 every year as Republic Day to commemorate the day it adopted its constitution in 1950.

The celebrations were held amid tight security conditions, coming a day after police shot and killed two suspected Pakistani militants near New Delhi.

Nearly 20,000 police and paramilitary forces were deployed across the city to prevent any attacks.

Other Indian cities and towns, particularly in Jammu and Kashmir state and the north-east, were also on high-alert and carried out celebrations under heavy security. (dpa)