Intelligence agencies on 25 January warned that Pakistan-based terror groups are likely to use Afghan Identity cards to cross the Indian border and carry out attacks ahead of Republic Day celebrations on 26 January.
The Delhi police have been directed to widen its searches and scan all buildings within 2.5 km of Rajpath, where the Republic Day parade is held every year.
The threats have prompted the Special Protection Group, which provides security to Prime Minister Narendra Modi along with some other top leaders of the country, to urge for enhanced security.
The ceremonial Republic Day parade is attended by President and Prime Minister and several other top dignitaries.
The Press Trust of India reported that agencies have been told in an advisory that "it is imperative for the security forces to be familiar with the range of threats for devising appropriate counter means as the use of conventional weapons by the terrorist and criminal groups is a part of a process to develop new techniques and tactics."
The advisory adds, "terrorists may use the uniform of security forces for fidayeen or suicide attacks."
The national capital has been brought under ground-to-air security cover with thousands of armed personnel keeping a tight vigil for the Republic Day celebrations here and police using anti-drone technology to thwart any aerial attack.
Along with armed personnel being deployed at strategic points, police have also ensured that CCTV cameras are installed at key locations. Meetings are being held to decide on the security arrangements and leaves of police personnel have been cancelled.
The entire Central and New Delhi region will have nearly 50,000 security personnel drawn from Delhi Police and central security forces guarding every nook and corner.
This time, police will use anti-drone technology to thwart any attack or identify any suspicious flying object, a senior police officer said.
Apart from this, security personnel will be stationed atop tall buildings with anti-aircraft guns. CCTV cameras have been installed and control rooms have been set up to monitor the feed from the cameras, the officer said.
Various security layers have been put in place and Delhi Police personnel along with paramilitary and NSG commandos have been deployed.
--With PTI inputs