30-year-old Yasin Bhatkal alias Mohammed Ahmed Siddhibappa, one of India's most wanted terrorist and also listed on the NIA Most Wanted list.
"The IM leader has been detained at the Indo-Nepal in Bihar and presently he is under Bihar police. His interrogation is going on and for further details he will be handed over to the NIA", Union home minister Sushilkumar Shinde said.
Yasin, along with three aides Tahaseen Akhtar Wasim Aktar Shaikh (23), Asadulla Akhtar Javed Akhtar (26) and Waqas alias Ahmed (26) were allegedly behind three coordinated bomb explosions at Opera House, Zaveri Zazaar and Dadar West in Mumbai on July 13, 2011, leaving 27 dead and 130 injured.
The IM leader is wanted in a string of terror attacks in Ahmedabad, Surat, Bangalore, Delhi and Hyderabad.
In February this year, the Maharashtra Anti-Terrorism Squad (ATS) had announced a reward of Rs 10 lakh each to anyone giving information on Yasin and the three aides.
Except Tahaseen, who planted a bomb in the Dadar blast, the rest three were also involved in the four co-ordinated low-intensity explosions, which struck the busy arterial road in the heart of Pune city on August 1, 2012.
Eight accused had been arrested in this connection. In December 2011, Delhi police had also announced a reward of Rs 15 lakh for any information leading to the arrest of Yasin in several terror cases, including three in Delhi.
While Yasin hails from Bhatkal in Karnataka, Tahaseen is from Samastipur in Bihar while Asadullah is from Azamgarh in Uttar Pradesh.
(with PTI inputs)