Indian police on Monday said they had made their first arrest in connection with last month's twin bombings which killed 16 people in the southern city of Hyderabad.
An official from the National Investigating Agency (NIA), a federal police unit that probes terror offences, said the suspect was arrested in the eastern Indian city of Ranchi.
"A NIA team arrested Manzar Imam in Ranchi in connection with the (Hyderabad) blasts," the official told AFP in New Delhi, asking not to be named and giving no further details.
Senior Ranchi police officer Vipul Shukla said the NIA had also been hunting for the man in connection with a string of bombings in the western Indian city of Ahmedabad which claimed 56 lives in 2008.
"He would be taken to (the southern state of) Kerala for interrogation by the NIA and Intelligence Bureau," Shukla told AFP by telephone from Ranchi.
As well as the 16 deaths, some 117 were also injured when two bombs exploded on February 21 in a mainly Hindu district in Hyderabad, a hub of India's computing industry in the southern state of Andhra Pradesh.
Newspapers have pointed the finger at the Indian Mujahideen, a shadowy militant group which has claimed responsibility for previous attacks but is seen by some experts as being simply a loose network of extremists.