They gathered in Parliament to pay floral tributes to the nine victims -- six Delhi Police personnel, two Parliament Security Service personnel and a gardener, who lost their lives on the day.

"India gratefully remembers those martyred while defending Parliament from terrorists on this day in 2001.

"Forces of hate and terror targeted what we cherish most -- India's democracy and democratic values. They did not succeed. And we will never let them succeed," the President tweeted.

Saluting their valour, Modi said "their heroism inspires every Indian".

On December 13, 2001, five terrorists infiltrated the Parliament House precincts and opened fire with automatic weapons. All five terrorists were killed in the counter-attack by security personnel.

Lok Sabha Speaker Sumitra Mahajan, veteran BJP leader L.K. Advani, Congress President Rahul Gandhi, BJP President Amit Shah, Leader of Opposition in Rajya Sabha Ghulam Nabi Azad, CPI National Secretary D.Raja and members from various parties and states paid their tributes.

Home Minister Rajnath Singh also remembered the martyrs for "exemplary courage and supreme sacrifice". "The nation will always remain indebted to their bravery and martyrdom," he tweeted.

Vice President M. Venkaiah Naidu, Union Ministers Arun Jaitley, Harsh Vardhan, Hardeep Singh Puri also took to Twitter to salute their courage.

West Bengal Chief Minister Mamata Banerjee tweeted: "Let us cherish the 'idea of India' for which our freedom fighters laid down their lives. Our people and our great institutions must strive to remain 'independent', in the true sense of the word."