A hospital official admitted that people were asked to leave. 'Though it caused inconvenience, such steps are necessary to ensure the safety of the people,' the official told IANS.

As hundreds of panicky and confused people suddenly poured out of the building, it caused a traffic jam outside on one of the busiest roads in the city.

But the RML Hospital, located not far from parliament, was not evacuated, medical superintendent N.K. Chaturvedi told IANS.

Intensive searches were also carried out at the Palika Kendra, which houses the New Delhi Municipal Council, and at Vikas Minar, the office of Delhi Development Authority (DDA).

The Palika Kendra is located in the very heart of the city, close to the Parliament Street police station. Vikas Minar is walking distance from the Deihi Police headquarters.

Thousands of employees were asked to leave both the buildings. 'Palika Kendra was evacuated,' NDMC spokesperson Anand Tiwari said.

The searches everywhere took about two hours to complete. In the end, the police ruled that every call was a prank.

'It was probably meant to cause panic,' a police officer said. 'The identity of the caller has not been established yet. We are investigating the matter.'