Police unearthed a mini ammunition dump in municipality employee-turned-gunrunner Nimai Das’s bathroom on Thursday.

The CID team that raided Das’s Rajarhat residence found 310 cartridges hidden in a cistern, including .22 bore bullets designed for the pen-pistols seized earlier from the Baguiati house of his arrested accomplice, fish vendor Anupam Chowdhury.

“No ordnance factory in the country manufactures ammunition resembling the 35 bullets of .22 bore that we found. The bullets were possibly imported from the UK,” an officer of the CID’s Special Operations Group said.

The ammunition haul includes 190 bullets of .303 bore with Czech markings. The rest are .315-bore cartridges.

Das, who is absconding, and his accomplices had supplied weapons and ammunition to both political leaders and Maoists in West Midnapore, according to one of the seven men arrested in Malda on Sunday.

The confessions of Ashok Mandal, one of the arrested men, had led to the raid on Chowdhury’s house and the recovery of a cache of arms, ammunition and armour — 7,000 bullets, three pen-pistols, 12 firearms and a bullet-proof jacket.

The additional director-general of the CID, Bhupinder Singh, had alerted the home department and the director-general of police, A.B. Vohra, to the possibility of VIPs being targeted with pen-pistols.

“We hadn’t seen a weapon like this one before. If a person carries it in his shirt pocket, nobody will suspect it is not a pen,” a senior CID officer said.

How potent is the easy-to-carry pen-pistol? “It has a range of 1.5 metres. If it is fired from close and the .22 bore bullet strikes the target’s chest or forehead, he/she can die,” said a ballistics expert.

S.N. Gupta, the deputy inspector-general of operations in the CID, said teams of sleuths had left for East and West Midnapore to investigate how many weapons Das and his accomplices had sold and to whom. “The arrested men have confessed to supplying arms and ammunition to Maoists during the turmoil in Nandigram. We are trying to trace the middlemen who introduced Mandal and his associates to the Maoists.”

The big fish is Das, a Group D employee of Rajarhat-Gopalpur Municipality who would often visit Allahabad to bring arms and ammunition for five to six “regular customers” in and around Calcutta, the police said.