Ahmedabad: Indian police announced on Saturday the arrest of ten people over a string of blasts that killed 49 people last month in western Ahmedabad city.

The "mastermind" of the July 27 attacks, which also left 160 people injured, was a cleric arrested in the northern Indian city of Lucknow, said Ahmedabad police chief P.C. Pandey.

"It rarely happens that the mastermind of such a conspiracy can be arrested so soon after an attack of this scale," he told a news conference here.

All the ten aged between 20 and 25 have been formally charged with murder and for "waging war against the state," Pandey said.

He did not rule out further arrests. If convicted, the suspects could face the death penalty.

"These men belong to the outlawed Students' Islamic Movement of India (SIMI) and were deeply involved in the attacks in Ahmedabad," Pandey said.

An Islamist group calling itself the Indian Mujahideen claimed responsibility for the Ahmedabad blasts.

"Indian Mujahideen is another name for SIMI -all one must do is to remove the 'S' and the last 'I' from the banned outfit to get the acronym of the group that claims responsibility," he said.

Serial bombings

Indian Mujahideen had sent an email to media organisations minutes before the terror attack - among the worst serial bombings in India - challenging security agencies to stop them.

Pandey said intelligence units in several Gujarat towns had uncovered the network of "SIMI sleeper cells". "It will help in solving the cases of other offensives across the country," he said.

Pandey described the string of 16 blasts as "diabolical" and labelled the arrests as a "great day for the Indian police."

The worst casualties occurred outside an Ahmedabad city hospital where a second round of blasts went off as ambulances raced in with those injured in the earlier attacks. The Ahmedabad bombings came a day after a series of bombings in the southern high-tech city of Bangalore that killed one person and injured eight.

In the Gujarati city of Surat, police found 18 unexploded bombs a day after the Ahmedabad carnage. Police chief Pandey said manufacturing defects had stopped them detonating.

Gujarat was the scene of deadly riots in 2002 in which at least 2,000 people, mainly Muslims, were hacked, shot and burnt to death after 59 Hindus died in a train fire first blamed on Muslims but later ruled to be accidental.