Elite anti-crime Rapid Action Battalion (RAB) arrested the three lawyers on terror financing charges.
"A unit of ours has arrested the three lawyers...We gathered information that they provided Taka 10 million to Shaheed Hamza Brigade (SHB) for weapon procurement...Legal initiatives are underway to quiz them," a RAB spokesman told reporters.
He said one of them was Barrister Shakila Farzana and identified others only as advocates Liton and Bapon, saying they were arrested from a residence in Dhaka's posh Dhanmondi area.
Officials earlier said SHB, a relatively small group, was formed in 2013 with a mission to stage an armed revolution against the "oppression of Muslims" at home and abroad.