In the verdict by a National Investigation Agency (NIA) court, all five accused in the 2007 Mecca Masjid Blast which killed nine people and injured 50 were acquitted.
The police have increased security in the communally sensitive city. More than 3,000 policemen and paramilitary troops were deployed as part of the security arrangements.
Senior police officials are monitoring the security arrangements at the historic mosque located near the iconic Charminar. Deputy Commissioner of Police V Satyanarayana said the police had taken all necessary measures to prevent any incident.
He said that the police will keep a close watch on the movement of people at sensitive places through CCTV cameras. The police would deal firmly with any attempt to disturb law and order, he added.
The court held that none of the charges framed against the accused were proved. A lawyer for one of the accused told reporters outside the Nampally criminal court complex that the judges held that the prosecution failed to prove the charges.
Ten people allegedly belonging to right-wing organisations were named as accused in the case. One of the accused, Sunil Joshi of Madhya Pradesh, a former Rashtriya Swayamsevak Sangh (RSS) member, was murdered while the case was being investigated. Swami Aseemanand, Devendra Gupta, Lokesh Sharma, Bharat Mohanlal Rateshwar alias Bharat Bhai and Rajendra Chowdhary also faced trial in the case. Two other accused -- Sandeep V Dange and Ramchandra Kalsangra -- are missing.
(With inputs from IANS)