Investigations have made little headway since Friday’s discovery of three underground bunkers stockpiled with the cough syrup Phensedyl close to the Bangladesh border in Nadia, with the BSF blaming local villagers’ silence and state police’s alleged failure to cooperate.

Neither has the smuggling network involved been identified, nor have the ownership details of the plot in Naghata village on which the bunkers had been built been unearthed.

Some 62,200 bottles of Phensedyl — a codeine-based cough syrup that has a market in Bangladesh as a recreational narcotic drug — had been found in the three bunkers, installed 2km from an unfenced portion of the international border. The haul is said to be worth ₹1.4 crore.

The BSF on Sunday handed the case over to the Narcotics Control Bureau (NCB) for further investigation "considering the gravity of the incident”, DIG Nilotpal Kumar Pandey, spokesperson for the BSF’s South Bengal Frontier, said.

An NCB team visited Naghata and inspected the bunkers and the cache of Phensedyl bottles. BSF officials said the bottles are likely to be submitted before a court in Krishnanagar on Monday.

A battle of attrition seemed to be taking shape between the BSF and the Bengal police, with the central force alleging a lack of cooperation from the district cops, who swatted away the charge.

Sources said the BSF-NCB investigation was facing challenges as the villagers were keeping their mouths shut — apparently for fear of the smuggling mafia — claiming ignorance about the ownership of the plot.

A local politician told this newspaper the plot where the bunkers were found belonged to “at least two individuals” but did not name anyone.

BSF officials said their investigations were also constrained by the need to avoid any political backlash from the local community, given that some people were ready to accuse the border force of overreach and highhandedness at the drop of a hat.

“So, we have restricted ourselves from venturing further to ensure nobody accuses us of encroaching on civic areas,” a senior BSF official in Calcutta said.

An official of the central force in Nadia expressed frustration at the lack of local police involvement.

“It’s surprising that the police have little knowledge about the landowners or the individuals behind the storage tanks (bunkers), although the area is under their surveillance. Everyone here seems to know, but they remain silent out of fear of the kingpins of this smuggling racket,” he said.

Another BSF official said: “What’s shocking is the police’s mysterious ignorance about the case — from the stockpiling of the Phensedyl to the building of the bunker-like storage tanks — despite their civic volunteers monitoring the area.”

By Sunday evening, the police had not questioned anyone in the village or attempted to locate the welder who fabricated the bunkers, made of corrugated metal sheets and bricks and fitted out with locking mechanisms.

The police said they had not registered a case or begun investigations because the BSF had not yet lodged a formal complaint with them.

Asked whether the BSF was deliberately sidelining the police from the investigation, DIG Pandey said: “The police can suo motu (on their own) take cognisance of the incident. But I shall refrain from commenting on why they have not done so.”

Police sources claimed they had unofficially carried out some preliminary investigations, which suggest the Phensedyl bottles may belong to an old batch that could not be sold in Bangladesh because of a declining demand.

“We suspect the consignment owner paid someone to hide the unsold items under the ground,” said the Krishnanagar superintendent of police, Amarnath K, dismissing the allegations of a police surveillance failure.

“It’s a success story of coordinated intelligence,” he said, alluding to the joint operation by teams from the BSF’s Tungi border outpost and Krishnaganj police that discovered the bunkers.

“If someone digs a pit behind their house, invisible to others, how can a civic police officer notice it? This is not a failure of intelligence but a success, as the operation was executed. The civic police do not have a sixth sense.”