The Rab intelligence men nabbed Hasanul Haq, 29, from his Jakir Hossain Road house in Mohammadpur, Director of Rab Intelligence Wing Lt Col Gulzar Uddin Ahmed told The Daily Star last night.

Claiming himself as an al-Qaeda member, he sent emails to the embassies of Japan and the Netherlands and the American Center.

He threatened that the embassies would be blown up if they do not stop interfering in the internal affairs of Bangladesh, Lt Col Gulzar said.

The embassies informed the National Security Intelligence and the home ministry about the emails and the ministry asked the Rab Intelligence Wing to investigate the matter and arrest the email sender.

Hasanul had also sent several emails to the Rab headquarters and its battalion office between June 18 and 22.

In the mails, Hasanul asked the Rab to release top criminal Arman and threatened to blow up the Rab headquarters and the battalion offices if Arman is not set free, said Gulzar.

"Checking the IP address of the emails, Rab first identified two cyber cafes in Lalmatia area from where the emails were sent. Later, they identified Hasanul as the sender of the mails," Gulzar said.

Hasanul, however, identified himself as Nazrul Islam in the emails. After his arrest, Hasanul told Rab that he had sent the emails using the name of Nazrul who is an NGO official so that he falls into trouble.

Gulzar said Hasanul is assistant accounts manager of Japan Garden City, a housing project in Mohammadpur. He claimed that he had completed masters in accounting from Jagannath University College.