The police have picked up three persons for questioning in connection with Saturday's terror attacks in Hyderabad as the Andhra Pradesh government said security agencies suspect Pakistan-based terror outfits Laskhar-e-Taiba or Jaish-e-Mohammad may be behind the blasts.

Among the three picked up is Mohammed Mustafa, a cycle shop owner, from Bibinagar, 25km from Hyderabad. Mustafa allegedly had links with a sleeper cell of a terrorist organisation from whom metal bearing balls used in the bombs were procured, sources added.

Hyderabad police commissioner Balwinder Singh said, "We have collected evidence from the blast sites and are hopeful that it will give clues about the groups involved in the terror strikes."

Declining to name the outfits responsible, he said the explosive substance used in the blasts was Neogel-90, a highly explosive ammonium nitrate, which was manufactured in Nagpur. In Delhi, Union home secretary Madhukar Gupta, when asked if any group has been identified as the mastermind, said that while the probe was at its initial stages, security agencies and state police suspected the role of LeT or JeM.

"Investigations into this incident are in a very preliminary stage and based on some information so far some possibilities have been identified and expressed," he said.

"These elements or organisations are clearly outside the country and they resort to fuelling such kinds of activities," Gupta said.