"We are already on high alert and taking all precautions in the run up to the R-Day celebrations," Delhi Police spokesman Rajan Bhagat told PTI.

In a pre-dawn encounter, the Uttar Pradesh ATS killed two suspected Pakistani militants in neighboring Noida while they were trying to enter Delhi.

The police have stepped up the security measures saying they do not want to take "any chance" ahead of the national event, especially in the backdrop of Mumbai carnage which claimed over 170 lives.

"After Mumbai attacks, we are not taking any chances.

There are inputs (about possible strikes). We are making tight arrangements for the event," a senior police officer said.

Security has been stepped up at important public places and vital installations, including the Delhi Metro stations, railway stations, bus terminals and crowded marketplaces.

Around 20,000 police personnel, including 5,500 from paramilitary forces, have been deployed across the city for the Republic Day, when the country showcases its military might, besides positioning several mobile hit teams.

Electronic surveillance will also be increased, the officer said, adding that extra security cover has been extended to all the religious places in the capital.