High-intensity explosives with timer devices were used in Saturday night's near-simultaneous bomb blasts in the city, officials said.
ML Kumawat, special secretary (internal security) Union ministry of home affairs, said investigations were on to find out the nature of explosives used, but police sources said Neo Gel 90, a class 2 explosive consisting of slurry and emulsifier, was used in the blasts.
Kumawat, who visited the blast sites along with other members of his team, said the nature of explosives would be known only after investigation by forensic experts.
A team of forensic experts from National Security Guards (NSG) also visited the site and gathered vital clues.
"It is premature to say which terror group is involved before the investigations are completed," he told newsmen at Gokul Chat, a popular eatery where the blast killed 32 people. Another 10 people were killed in the blast at Lumbini Park.
"It is a cowardly act. All those killed were innocents," said the official. He did not agree that the failure of intelligence led to the blasts.
"The city is big. The intelligence agencies didn't know at which place and when they (terrorists) would strike," he said, admitting that they had information after the May 18 blast at the Mecca Masjid that terrorists could strike again.
O Narasimha Murthy, director, Andhra Pradesh Forensic Science Laboratory (APFSL), said the explosives used were of high intensity. "Timer devices were attached to the explosives," he said.
Murthy said two teams of the forensic laboratory were gathering clues to know the nature of explosives used.
However, police sources said the explosive used in the blasts was Neo Gel 90, manufactured by Ameen Chemicals at Nagpur. This was the explosive found in the unexploded bomb recovered from under the Malakpet foot over bridge last night, hours after the blasts.
Police are suspecting the involvement of the Bangladesh-based Harkat Ul Jihad Al Islami (HUJI) and Pakistan-based Jaish-e-Mohammed. Sources said the sleeper cells of the two terror groups could have triggered the blasts. HUJI was also blamed for the bomb blast at the historic Mecca Masjid, which had claimed nine lives.
The man who is once again under the police scanner is Shahed alias Bilal, a HUJI activist believed to be the mastermind behind the mosque blast and the suspected suicide attack at the office of the police commissioner's task force in 2005 here. One policeman was killed in that attack.
A native of Hyderabad, Bilal had disappeared a few years ago. He is believed to be in Bangladesh and blamed for many terror attacks in south India in recent years.