Three men, including a British citizen, have been arrested over the murders of two secular bloggers in Bangladesh, authorities said.
The three men are suspected members of the Ansarullah Bangla Team, a banned Islamic militant outfit, said Major Maksudul Alam, a spokesman for the country's Rapid Action Battalion.
Bangladesh banned the group in May after police accused it of threatening and killing bloggers and writers.
Mr Alam said one of the arrested men, Touhidur Rahman - a British citizen of Bangladeshi origin - was the mastermind and financier of the attacks on bloggers Avijit Roy and Ananta Bijoy Das, who were killed earlier this year.
The suspects were arrested on Monday night in raids in Dhaka, Bangladesh's capital, and appeared with authorities at a news briefing on Tuesday.
Mufti Mahmud Khan, the head of the battalion's media wing, told reporters that while Rahman was the main planner of the killings, another suspect who was arrested, Sadek Ali, acted as a bridge to communicate with Mufti Jasim Rahmani, the alleged head of the group.
Rahmani is currently in jail awaiting trial over the murder of another blogger, Ahmed Rajib Haider, in Dhaka in 2013.
"Ali often visited the prison to meet Rahmani for instructions," Mr Khan said.
He said the third suspect, Aminul Mollick, was a broker at a passport office, where he helped members of the militant group make fake passports so that they could travel abroad if necessary.
The battalion did not allow the detainees to talk to reporters at the news briefing.
Mr Khan said Rahman is an information technology expert and returned to Bangladesh from the United Kingdom in either 2011 or 2012. He then got in touch with Rahmani, who inspired him to work for the group, he said.
"He is the main planner of all the recent killings of the bloggers," Mr Khan said.