A taskforce of combined intelligence officials is interrogating the four, who were arrested from Sylhet division on Saturday and Sunday, to extract detailed information about their involvement in the attack and the masterminds behind them.

HuJi leader Abdur Rouf, who was arrested along with 26 others in Bhaluka in Mymensingh on August 2, may also be brought before them for the same purpose.

Sources said, HuJi leader Hannan, now in jail since his arrest on October 1 last year, never admitted, during extensive interrogation, to have been involved or to have had any link with the attack on Anwar Choudhury in Hazrat Shahjalal Shrine in Sylhet.

Three people died and 70 others were injured in the grenade attack on the Bangladesh-born British high commissioner at the shrine on May 21, 2004.

A few of the arrestees admitted their involvement in the attack and investigators learnt about their link with HuJi and Mufti Hannan, which they will have to cross-examine for confirmation, said a source.

"We are now trying to get details of the attack. We will then verify their statements. If we feel anything is missing, we might bring Hannan for further quizzing," said an investigator seeking anonymity.

The investigators will have to be certain that the information the four arrestees gave is correct.

Sources said it would take a few more days to verify their information and come to a primary conclusion. The investigators did not agree to disclose anything more about their findings.

Criminal Investigation Department (CID) took the four arrestees -- Sharif Sahedul alias Bipul of Chandpur, Badrul Alam Mizan of Habiganj, Hafej Nayeemur Rahman Arif of Sunamganj, and Delwar Hossain Ripon of Moulvibazar -- on a 10-day remand on Monday in suspicion of involvement with the attack on the British envoy in Dhaka.

Two of the arrestees admitted to their involvements in the attack.