Bangladesh's elite security force have arrested the head of a banned group over the murders of two atheist bloggers which sparked an international outcry.
The Rapid Action Battalion (RAB) arrested Mohammad Abul Bashar, the head of the Ansarullah Bangla Team (ABT) which was banned in May over a series of killings of bloggers.
Mufti Mahmud Khan, a spokesman for the RAB, told the AFP news agency that two other members of the ABT were also arrested in the capital Dhaka.
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"All three are the suspects in the murders of bloggers Avijit Roy and Ananta Bijoy Das," Khan said, referring to the writers who were killed earlier this year.
Four secular bloggers have been hacked to death in Bangladesh since the start of the year, including Roy and Das, sparking international condemnation and protests mainly by secular activists in the capital.
Bashar, 43, is the most high profile person to have been arrested in connection with the murders this year and the move came after a series of arrests in the past few weeks.
"We arrested them in the capital's Fakirerpool neighbourhood this morning. They were planning to flee the country," RAB Major Kamran Kabir told AFP.
"Among those we've arrested in connection with the blogger murders in recent weeks, Bashar is the biggest fish."
Khan said Bashar took over leadership of the ABT after Jashim Uddin Rahman, his older brother who is the group's founder and spiritual leader, was arrested in 2013 over the murder of another blogger, Ahmed Rajib Haider.
Rahmani ordered the murders of the bloggers from his jail cell this year, a message that Bashar took to their followers, the RAB has said previously.
The RAB hailed the arrest of Bashar as a "major success" in the force's efforts to hunt down the killers of the bloggers.
The two others arrested on Thursday, Julhas Biswas and Jafran al Hasan, "took part in the killing mission" of the two bloggers and tweeted admitting the group's role in the murders on the internet, the RAB has said previously.
"These two are members of the media branch of the ABT," Khan said Thursday, referring to the group's PR team.
Roy, a US citizen who was born in Bangladesh, was murdered in February by a gang wielding machetes in Dhaka.
Das, 33, was killed in a similar fashion as he went to work at a bank in the northeastern city of Sylhet on May 13.
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Prime Minister Sheikh Hasina's secular government has vowed to hunt down the killers, following international outrage and accusations it failed to stop the attacks, wary of a political backlash.
Police have stepped up security for those being threatened amid claims of an alleged hit-list of bloggers to be killed.
Last week, five ABT members were charged over the murder of atheist blogger Washiqur Rahman, who was killed in March.
At least 12 atheist bloggers have fled the country in the wake of the murders and 70 bloggers have asked for assistance for migration as their lives are at stake, according to Berlin-based atheist blogger Asif Mohiuddin.