T Srinivas Rao, judge of the seventh additional metropolitan sessions court here, absolved the accused, nine of whom were in jail.
A Bangladeshi bomber had walked into the Task Force office located in Greenlands area here on October 12, 2005 and detonated an Improvised Explosive Device (IED), killing the home guard and himself.
A special investigation team (SIT) of the Central Crime Station conducted an inquiry and suspected the role of an international terror organisation in the blast.
The investigating team later filed a charge sheet and named a total of 20 persons in it. The SIT arrested 10 persons and claimed that three other accused died in different incidents and the remaining seven were absconding.
The counsel representing six of the 10 arrested accused, Mohammed Abdul Azeem, told PTI that while one of the 10 arrested men got bail, the other nine were still in prison.
When contacted, Deputy Commissioner of Police (Detective Department) Avinash Mohanty said they will study the court order and then decide whether to go for an appeal against the judgement.
Reacting to the judgement, MIM chief Asaduddin Owaisi in questioned whether the the investigating officers will be made accountable.
"In the 2005 Hyd task (force) office bomb Blast( case, police couldn't prove conspiracy , but the accused lost 10 years of their lives languishing in jails," Mr Owaisi tweeted.
The SIT filed the chargesheet in 2006.