Intelligence officials are also trying to gather details about Waliur Rahman, chief of the NGO named Manabmukti Samajkalyan Sangstha (MSS), and its activities.

They visited the MSS office yesterday, took video footage of the spot and quizzed a number of neighbouring shopkeepers to know whereabouts of Waliur.

An investigator seeking anonymity said their initial suspicion is the injured youths -- Kazi Mohammadullah Sohag, who claims to be an NGO worker, and critically injured Khorshed Alam Ripon, a criminal on the run -- are members of some local criminal gang.

They are also inquiring whether the youths are linked with any outlawed group, as there are intelligence reports on the market being used as hideouts by different outlawed outfits, he added.

Police confirmed that Ripon was a member of Gopal-Babul Gang of Farmgate and lived in Kathalbagan before going underground. But they are yet to find out the address of Waliur.

"We are hopeful of finding out the whereabouts of Waliur and the activities of the NGO after we start grilling Sohag taking him in remand," said the deputy commissioner of (South) of Dhaka Metropolitan Police.

Ramna police yesterday produced Sohagh before the Court of Chief Metropolitan Magistrate, Dhaka with a petition for seven-day remand. The court granted five days.

Police could not quiz Ripon as he is still in a critical condition. He was shifted to BDR Hospital at Pilkhana from Orthopaedic Hospital Friday night as his condition deteriorated.

Police sources said Ripon was taken to the well-secured BDR hospital suspecting his fellow gangsters might try to kill him.

Every day a large number of people visit the market that houses over 500 shops and residential flats but does not have any security or surveillance system.

In May police arrested four operatives of banned Purbo Banglar Communist Party (PBCP) -- Mahfuzur Rahman Jewel, Abdur Razzak, Ali Tareq and Shafi Sarker -- at the market in two separate operations.

Razzak was regional publicity commander of Rajshahi and Tarek of Khulna, while Shafi was a computer operator of Lal Pataka faction of PBCP. They were drafting PBCP handbills on the second floor of the market.