The Border Security Force has stepped up vigil near the India-Pakistan border in Punjab amid increasing attempts by smugglers to push narcotics and weapons through drones under the cover of dense fog, an official said.

Drone movements from across the border to push weapons and heroin into Indian territory have gone up considerably in the past few days in the wake of dense fog enveloping the region.

"We have increased patrolling and 'nakas' (checkpoints) and BSF (Border Security Force) personnel are alert to thwart any bid by smugglers," said a senior agency official.

A Punjab Police official said the movement of over 200 Pakistani drones had been recorded near the international border this year.

The officials said smugglers had increased their activities along the international border as the area was blanketed by dense fog.

With the fog reducing visibility to almost zero, BSF troops are relying on the buzzing noise to intercept unmanned aerial vehicles entering from Pakistan.

In just one month, BSF personnel have gunned down eight drones, including hexacopters with six rotors, near the border areas, the BSF official said.

Frequent drone movements have been recorded in Amritsar, Tarn Taran and Fazilka districts, especially during the nights and early mornings, he said.

The smugglers have also started covering the lights on the drones using adhesive tape so that they cannot be sighted.

Earlier this month, BSF troops recovered 25 kg heroin, a pistol and 50 rounds of ammunition, allegedly dropped from a Pakistani drone near the border in Fazilka, he said.

The smugglers are also using other modes to push narcotics into the country.

On Wednesday, the BSF recovered another 25 kg of suspected heroin from a farming field in Fazilka around 2 am.

The troops were alerted after noticing some activity on both sides of the border fence near the Gatti Ajaib Singh village.

BSF troops fired towards Pakistani smugglers ahead of the border fence. However, the smugglers managed to run away taking advantage of the dense fog.

Later, during a search of the area, 25 packets of suspected heroin and a PVC pipe were recovered, another BSF official said.