Calcutta, April 2: Calcutta police today arrested a Maoist leader suspected to have masterminded the blast targeting Buddhadeb Bhattacharjee's convoy in Salboni in 2008 and the massacre of 24 Eastern Frontier Rifles jawans in Shilda in 2010.

The arrest comes two days before the former rebel hotbed of Jungle Mahal votes.

The special task force (STF) of the city police picked up Mansaram Hebram alias Bikash, secretary of the state military commission of the CPI Maoist and state secretariat member of the outfit, and his wife Tara from the Maidan area.

"Acting on specific information, we arrested Bikash and his wife from the Maidan area of Calcutta this afternoon. Following leads from the two, we raided a house in Mogra, Hooghly, and seized an AK-47 rifle and 120 rounds of ammunition," said Vishal Garg, deputy commissioner of police, STF.

"We have seized a 7.62mm revolver, nine rounds of ammunition and some Maoist booklets from Bikash. We have learnt that Bikash and Tara had come to Calcutta to meet a person. We are looking for that person," Garg added.

Some police sources, however, said Bikash and Tara may have surrendered.

Bikash, who was an aide to slain guerrilla leader Kishan, and Tara have been charged with sedition and also booked in an arms-related case. They will be produced in the city sessions court tomorrow.

Tara is a member of the CPI Maoist's squad in Salboni, West Midnapore, and is an "expert" in detonating bombs. She is suspected to have taken part in several gun battles with security forces.

After the blast targeting then chief minister Bhattacharjee's convoy in Salboni, Bikash had claimed he had masterminded it.

Bikash is among the few tribal Maoist leaders in Bengal to have risen to such a high post in the CPI Maoist. Usually, the outfit's leadership positions are given to city-bred comrades.

Police sources said Bikash had also led the attack on Sankrail police station in Howrah in 2009 in which two cops were killed and the officer-in-charge was abducted.

During the Maoist siege of Lalgarh in 2008-2009, Bikash is suspected to have led the "capture" of Dharampur, which was a CPM bastion.

After People's Committee Against Police Atrocities activists demolished the house of CPM leader Anuj Pandey in Dharampur in 2009, Bikash had appeared before the media, his face covered. Within a week, central security forces entered Lalgarh and he went underground.

The police sources said that four more senior Bengal Maoist leaders were still at large. They are Akash, the state secretary of the rebel outfit who recently issued a statement calling for a boycott of the Assembly elections, Madan, Jayanta and Ranjit.

According to the sources, the four are trying to regain ground in Jungle Mahal.