Parliament resumed business at 1500 IST after a bomb hoax around 1200 IST forced adjournment of both Houses on Friday.
Acting on a specific information that a bomb could have been planted in the building, Rajya Sabha Chairman Bhairon Singh Shekhawat and Lok Sabha Speaker Somnath Chatterjee adjourned the Houses at 1200 IST and asked members to vacate the premises immediately.
Bomb detection and disposal squads rushed to the complex.
Security personnel went on high alert both inside and outside the complex, which was virtually turned into a fortress.
The prime minister, who had just finished his meeting with Tamil Nadu Chief Minister Jayalalithaa, was escorted out of the building to his office in South Block, about one kilometre from Parliament.
He was kept informed about the minute-to-minute developments.
All ministers, members of Parliament, staff and media persons were asked to come out in the open lawns. All the roads leading to Parliament House and nearby South and North Blocks, housing the offices of prime minister and the key ministries of defence, home and finance, were sealed.
After about 90 minutes of intensive combing, Home Minister Shivraj Patil gave the all-clear sign. He said the information about the bomb threat had originated from Chennai and was received both by the Intelligence Bureau and the US Embassy.
Without divulging details, Patil said the place from where the information originated had been tracked and security agencies were investigating.
"I think everything is all right. The whole thing is being inquired into. We don't want to take any chance," Patil said.
Teams of elite National Security Guards also helped in the second round of the searches.
Parliamentary Affairs Minister Priyaranjan Dasmunshi, who was in the Lok Sabha, said the security chief, on getting the information, rushed to the Secretary General P D T Achary when the Question Hour was on.
Achary immediately consulted the speaker who had quick word with Dasmunishi and adjourned the House till 1300 hours. A similar exercise was carried out in the Rajya Sabha.
Chatterjee said adjourning the House after receiving the information was a precautionary exercise and not out of fear.
"Fortunately, nothing was there but we could not take a risk," the Speaker said.
Asserting that there was no question of being terrorised, he said, "Indian Parliament is not fragile and we are ready to face any eventuality."
On December 13, 2001, five heavily-armed terrorists of Pakistan-based Jaish-e-Mohammad, travelling in a White Ambassador car with red beacon light, stormed the Parliament House complex.
One of the attackers blew himself up in front of the main entrance while others were shot dead by the security forces in an intense gun-battle before they could enter the building where almost the entire political leadership was present.
The entire security apparatus was overhauled following the attack with hi-tech gadgets being installed at at a cost of over Rs 100 crore.
The security was made multi-layered with gadgets like tyre-killers and boom lifters were put in place. Special electronically activated I-cards were also introduced for all the MPs, staffers and media persons as an extra protective measure.
(With agency inputs)