A day after US warned of attacks by Al Qaeda in India, the Delhi police on Saturday said it has "specific intelligence inputs" that terror groups would try to carry out deadly strikes to subvert Independence Day celebrations in Delhi and has beefed up security measures.

In view of the "considerable escalation in threat perception", an unprecedented ground-to-air security apparatus has been put in place for the annual national event in Delhi to be attended by Prime Minister Manmohan Singh and the entire top political and military leadership of the country. 

"We are already aware of that... Intelligence agencies have already indicated," Special Commissioner (Security) Ajay Chadha said when asked to comment on warnings given by the US about attacks by foreign militants in Delhi and in Mumbai.

Police have received a number of general inputs and "a few specific ones" about possible strikes in Delhi, and the Mumbai blasts and unearthing of a terror plot in London to blow up passenger aircraft have given credence to the intelligence reports, he added.

The inputs include terrorist plans to "target prominent political leaders and symbols of national importance," he added.

Keeping in mind the volatile situation, elaborate security arrangements have been made for Independence Day celebrations and Janmashtami festival and over 10,000 police personnel and commandoes of the ITBP and National Security Guards have been deployed in Delhi, he added.

A multi-tier security apparatus has been thrown in and around the historic Red Fort, from where the prime minister will address the nation, with special emphasis given on anti-sabotage and anti-explosive checks and tight access control measures.

Aerial surveillance by policemen in military helicopters, deployment of Air Defence Guns and positioning of Quick Reaction Teams on roof-tops in the vicinity of Red Fort are among the measures taken for ensuring a trouble-free function.