Do you often ask the vendor, who hawks down your lane, to deliver the vegetables at your doorstep? Or are you one of those who invite the kabariwala into the drawing room to weigh the scrap? Think twice before you do that the next time ? the unassuming man might soon burgle your house.

Police have come across such cases where the vendor has turned out to be a tip-off person for a gang, or worse still, a burglar himself.

The revelation comes following a string of recent arrests in north Calcutta, where the burglars had picked their targets ? rich flat-owners ? after a recce posing as a vendor.

The trend has left the police top brass rattled, prompting detective chief Gyanwant Singh to seek for dossiers on the criminals operating in various zones from the respective divisional deputy commissioners of police.

?A list of criminals operating in this region has been handed over to the detective department but it would not be proper to comment about it now,? said Javed Shamim, deputy commissioner of police (Eastern Suburban Division).

During a recent joint raid by the Chitpur and Ultadanga police, 35-year-old Sk Hasmi was rounded up in Koila Patti, in Ultadanga. The self-styled operator would come to the city daily from Ghatakpur, in Bhangore, and move around in pockets of north Calcutta posing as a kabariwala.

On one of his rounds, Hasmi had entered the flat of Mahendra Prasad Agarwal. Later, on a day when the residents were not around, he broke into the flat and made away with ornaments and cash worth over Rs 2 lakh.

?In almost all the cases, he had previously visited the house,? said a senior officer of Chitpur police station.

A few days later, Cossipore police arrested Pappu Das from Bediapara, in Dum Dum. A burglar, Pappu also worked as tip-off man for gangs operating in the adjoining areas. During investigations, Pappu revealed that there were several others operating in a similar fashion in the Tallah, Chitpur, Cossipore, Ultadanga and Maniktala areas.

?Some of the vendors double as decoys and burglars. At times, they also take help from local rickshaw-pullers. A hunt is on for them,? said Barun Mullick, deputy commissioner of police (North).