They said some 50 to 60 robbers work in the private security agencies and collect information about the jewellers while guarding the shops or shopping complexes. They work as sources of the robbers' gang.

"They help their godfathers in planning such robberies and take part in the operations," said a CID official. He said the gang is so strong and well-organised that the main criminals still remain untraced.

The police and the intelligence agencies said this gang was involved in the recent 4,500-tola gold looting from Venus Jewellers in Gulshan. On August 28, the robbers entered the showroom through a ventilation shaft in the ceiling of Navana Shopping Complex and looted the gold ornaments as the market was closed for weekly holiday.

Police could not yet recover the looted jewellery but they picked up 17 members of private security agencies, Cobra and Martinet, who were on duty at the market.

"The way the looting took place is mysterious. All collapsible gates were closed during the incident. We suspect that the workers of the shop and the security personnel of the market were involved," said DMP Commissioner SM Mizanur Rahman.

After a series of gold robberies in the last few months, jewellers are in fear of such incidents. Bangladesh Jewellery Samity (BJS), which represents 800 of the around 1,000 owners of gold shops, observed a strike on August 29 to protest the gold heist.

According to BJS, more than Tk 1,000 crore has been invested in the gold showrooms in the capital. Private security personnel guard these shops.

"The authorities should deploy police from 9:00pm to 6:00am to ensure security of gold shops," BJS President MA Wadud Khan said. He also indicated that the security guards might have been involved in the gold heist.

"The service of the private security agencies is not up to the mark and some of these agencies' members have become a serious threat for us," Wadud alleged.

The private security agencies also suspect that some of their members may have link to the robbers due to lack of proper screening before their appointment.

"All the security agencies should have internal security department to verify the members' full profiles and backgrounds," said Selim Chowdhury, managing director of Group-4, a leading private security agency.

Five major gold robberies took place in the city markets -- Navana, Rapa Plaza, City Heart and Amir Complex -- since early this year. A total of 19 robberies occurred since 1998 and police could not trace the robbers and their godfathers.

CID officials said in most of the cases they found involvement of security guards.

Most of the city's gold showrooms are located in the Baitul Mukarram market, Chandni Chawk, Mouchack, New Market, Eastern Plaza, Paltan Super Market, Rajdhani Super Market, Navana Shopping Complex and Iqbal Centre.

"The recovery of the looted good is not satisfactory. So far the police have failed to find out the gang. This encourages them to plan robberies one after another," Wadud said. "Nobody knows who is the next target."

"We may consider the proposal for police deployment at night at popular gold markets," the DMP commissioner told Star City.