A team of the elite police unit whisked him away from his office at Dhaka's Banglamotor on Thursday afternoon.
Habibul is Managing Director of Information Service Network.
His sister Dhaka University Professor Shaheen Islam told bdnews24.com that some RAB personnel picked her brother up from his office around 1:30pm and asked the ISN employees to follow them on another car to the RAB-1 offices in Uttara.
RAB spokesperson Mufti Mahmud Khan told bdnews24.com that they would question the freedom fighter over a South African ring of fraudsters currently operating in Bangladesh.
The ring earns money through dupery and sends those abroad, according to Khan.
"Somehow Habibul and the ring had communication. He may be a victim," he said.
He said the decorated freedom fighter was not arrested.
After releasing him around 8:30pm, RAB-1 Commander Lt Col Sarwar Bin Kashem told bdnews24.com that the ring tricked a bank manager and embezzled tens of millions of taka of the banker.
"We found that the number used by the gang to communicate with the bank manager was also used to talk to Habibul Alam," Sarwar said.
"But he is also a victim of their dupery. We released him after hearing the details from him," he added.
Habibul was a member of Crack Platoon, a group of guerrillas that conducted operations against the Pakistani occupation forces and their local collaborators in Dhaka during the Liberation War.