NEW DELHI: Senior Congress leader Ghulam Nabi Azad on Monday raised questions on the functioning of the National Investigation Agency (NIA) after a court acquitted right-wing activist Swami Aseemanand and four others in the 2007 Mecca Masjid blast case investigated by the central agency.

"It (acquittal) is happening in each case since the government was formed four years ago...people are losing faith in the agencies," he told news channels.

A special anti-terror court on Monday acquitted the five men in the 2007 Mecca Masjid blast case, ruling that the prosecution failed to prove charges against them.

A massive blast had ripped through the Mecca Masjid in Hyderabad on May 18, 2007, during Friday prayers, killing nine people and wounding 58.

When asked about the verdict, former Union home minister and Congress leader Shivraj Patil said, "I find it very difficult to say whether this is wrong or correct".

He said he was not aware of the nature of charge-sheet filed by the probe agency, statements made by the witnesses and the cross-examination done by the prosecution.

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.