The surprise arrests have indicated a change of course for police, who have blamed Muslim activists for a wave of bombings that have killed more than 145 people across the country since May.

Ascetic on a motorcycle

Among those arrested is a sadhvi or woman ascetic called Pragya Singh, who was detained by Mumbai authorities on allegations that her motorcycle was used in the attack. Police said Singh, who is in her late 20s, might also have helped plan the attack. The bomb used in the attack was placed on a motorcycle and exploded amid a crowd.

Also being questioned for the Malegaon and Modasa bomb blasts last month is a retired army major. The ex-army officer is said to have once headed a BJP ex-servicemen cell in Mumbai.

While investigations have yet to unravel the full conspiracy police say some of those arrested have links with a Hindu right wing group, ‘Hindu Jagran Manch’.

Members of these groups have been accused of involvement in recent attacks on Christians in the eastern state of Orissa leaving more than 40 people dead. More than 20,000 Christians in the district of Kandhamal fled their homes for state-run camps.

Calls for a ban on extremist Hindu groups, including the right wing Vishwa Hindu Parishad or World Hindu Council, gained momentum among some political groups.

Protests by Hindu groups

The arrests sparked off protests in Vadodara, a city in the state of Gujarat, by Hindu groups who burnt effigies of neighbouring Maharashtra’s chief minister Vilas Rao Deshmukh warning him to release the Hindu activists and not dub them as terrorists.

Jagan Patel, a youth leader, joined the protests. "Hindus have never indulged in such acts and will never be involved even in the future", he said. "We want the Maharastra chief minister, Vilas Rao Deshmukh and his home minister R. R. Patil to treat Hindus well or face the consequences."

A group called the Indian Mujahideen claimed responsibility for some of the terror attacks across Indian cities in the last few months and police arrested over 30 Muslim youth believed to be part of the conspiracy. But the law enforcement agencies have till date not come up with decisive proof concerning their involvement in terror acts. The arrests of Hindu activists are regarded by many as a major development in the police investigation.