Both houses of the parliament were adjourned at about 11:48am during the question hour, soon after their presiding officers Lok Sabha Speaker Somnath Chatterjee and Rajya Sabha Chairman Bhairon Singh Shekhawat had received communications to the effect that a bomb had been planted somewhere on the parliament premises.

Bomb disposal squads of the Army and the elite National Security Guards, which were promptly called in, searched the entire parliament complex for possible explosives and gave an all-clear signal after about an hour and a half.

Indian Home Minister Shivraj Patil told reporters here that a security alert was issued and the parliament was emptied of its members and ministers soon after information from Chennai had been received by the Intelligence Bureau and the American Embassy here about the presence of explosives in the complex.

He said efforts were on to check whether the information about a bomb in the parliament had originated in Chennai city or a place outside it.

Initial reports suggested that the American Embassy had alerted the Indian Intelligence Bureau about the presence of explosives in the parliament and the bureau in turn put the parliament security establishment on alert.

David Kennedy, a spokesman of the US mission here, declined to confirm or deny whether it had received any e-mail regarding the presence of explosives in the parliament or had it alerted the Indian authorities about it. "We do not discuss in public security cooperation between India and the US."

Within minutes after receiving the security alert, the prime minister was escorted out of the parliament complex and soon after that all members of the parliament belonging to different political parties including the home minister, Defence Minister Pranab Mukherjee and Parliamentary Affairs Minister Priyaranjan Dasmunshi left the parliament premises.

The security officials with mine detectors and sniffer dogs searched every nook and cranny of the parliament complex but found nothing after the first round of thorough check, Shivraj Patil told reporters.

He said to be doubly sure the security personnel conducted a second round of search of the entire premises, where 543 members of Lok Sabha and 250 members of Rajya Sabha besides the ministers and senior government officials are present on any given day.

"After the first search, the officers told me that the entire complex has been checked and everything is alright and nothing has been found. There is nothing to worry," Patil said.

Both houses of the parliament resumed their sessions at 3:00pm after the two rounds of intensive search that went on for nearly three hours.

Initially, the parliament was adjourned till 1:00pm, which was later extended to 3:00pm to enable the security officials to conduct the searches.

The security alert came just three days after the parliament had observed the fourth anniversary of the December 13, 2001 terrorist attack on it, which had left 11 people dead.

Asked if the information about bomb was a hoax, Dasmunshi told reporters here, "I cannot say if it is hoax or real. Only security personnel can say that."