Police launched a massive search operation across the city following four bomb threat calls on Tuesday morning.
An anonymous caller rang up the police main control room around 1030 hrs and informed about bombs placed at Secunderabad railway station, passport office, Swathi tiffin centre and at a bus stop all under the limits of Secunderabad, police told PTI.
Bomb disposal squads have been dispatched to the locations and they are thoroughly checking the areas.
According to preliminary investigations, the caller reportedly used his cell phone and police were trying to trace the caller.
Meanwhile, police personnel have also begun intensive search and frisking operations at all the major junctions across the twin cities of Hyderabad and Secunderabad.
City police are also taking no chance with regard to security arrangements and have intensified searches.
Over 40 persons were killed in two blasts in Hyderabad on August 26, 2007.