Over 1,500 personnel drawn from different wings of the Hyderabad City Police were deployed in strategic locations in the Old City, a senior police official said.
"An alert has been sounded and it is continuing. Our watch is on the entire city and we are monitoring through CCTV cameras installed across the city. Elaborate security arrangements are in place," the official said.
Deputy Commissioner of Police (DCP), South Zone, V Satyanaryana along with senior police officials supervised the security arrangements at the historic Mecca Masjid and its nearby areas.
"To prevent any untoward incident, over 1,500 police personnel have been deployed in the Old City. The situation is peaceful," the DCP told PTI.
Earlier in the day, a special National Investigation Agency (NIA) court acquitted five persons, including right-wing activist Swami Aseemanand in the case, ruling that the prosecution failed to prove charges against them.
A powerful blast, triggered by remote control, had ripped through the over four-century-old mosque here on May 18, 2007, when devotees had gathered for Friday prayers, killing nine people and wounding 58.
The case was initially probed by the local police before being transferred to the CBI, and finally in 2011 to the NIA, the country's premier anti-terror investigation agency.