The heightened terrorist threat to the national capital triggered by the attack on Parliament on December 13, 2001, has forced the authorities to shorten the route of the main Republic Day parade for the second year in succession.

In view of concerns about security, the route for this year's parade will also be shortened by 3km from the traditional 11km, as was done last year, police and defence sources in New Delhi said on Monday.

The authorities decided to skip some congested areas of Old Delhi after security agencies voiced apprehensions about the protection of marching contingents and various tableaux of the defence forces, ministries and states. The agencies felt that it would be easier for a terrorist group, particularly a suicide squad, to attack the parade in these areas.

The route of the parade, which starts from Vijay Chowk, marches down the historic Rajpath and culminates at the Red Fort after criss-crossing many areas of the city, was curtailed for the first time in 50 years last year when the threat perception heightened following the attack on Parliament.

Intelligence agencies have warned that terrorist groups Lashkar-e-Tayiba and Jaish-e-Mohammad may try to disrupt the celebrations by carrying out suicide attacks on the parade route or attacking soft targets elsewhere in the capital. These reports even fear that some terrorists may already have sneaked into the capital. This has prompted police to carry out random checks.

Meanwhile, top officers of the Delhi police, the armed forces and other security agencies are holding regular meetings to ensure proper security for the parade and the country's top VVIPs, including President A P J Abdul Kalam, Prime Minister Atal Bihari Vajpayee, Deputy Prime Minister Lal Kishenchand Advani and Congress president Sonia Gandhi.

Policemen and sleuths of intelligence agencies have been deployed at various places along the route and night vigil has been stepped up a week ahead of the celebration.

"The security is of high grade," Deputy Commissioner of Police [New Delhi] Manoj Lall said. "Everything has been tied up and a constant scrutiny of the security is being conducted."

DCP [Central] Arvind Deep said, "All measures have been taken to ensure foolproof security."