Officers said drones flew low to avoid detection, may have dropped around 80 kgs of weapons between Sept 9 and 16.

New Delhi: Indian Air Force bases in Jammu and Kashmir have been put on high alert following the discovery of a burnt drone in Punjab’s Tarn Taran which security forces believe was used to drop ammunition this side of the border from Pakistan.

The bases under ‘orange alert’ are Awantipora, Jammu, Pathankot and Hindon.

Probing further, officers surmised that these heavy-lifting drones from Pakistan made at least eight sorties in 10 days to drop the weapons including satellite phones.

On Monday, four terrorists of the Khalistan Zindabad Force were arrested in Punjab's Tarn Taran district. Five AK-47 rifles, which weigh about four kilograms with magazine, four Chinese pistols, nine HE grenades, Rs 10 lakh fake currency, 1000 rounds of ammunition and two electronic receivers, were recovered.

The terrorists have been identified as Balwant Singh, Akashdeep Singh, Harbhajan Singh and Balbir Singh. Both Akashdeep Singh and Balwant Singh have multiple criminal cases against them.

Another consignment was also intercepted which contained five satellite phones and a large number of AK-47 assault rifles. This has led officials to believe that the arms and phones were for Jammu and Kashmir since mobile communication is still snapped there.

Intelligence agencies believe a module of 8 to 10 Jaish-e-Mohammed (JeM) terrorists could also try to carry out a suicide attack at Air Force bases in and around Jammu and Kashmir, news agency ANI reported.

Officers said the drones flew low to avoid detection and may have dropped around 80 kgs of weapons between September 9 and 16.

The investigation involved multiple agencies – the Punjab Police, central security agencies, the Border Security Force, the Indian Air Force. Prima facie evidence found that multiple Chinese commercial drones with 10 kg payloads were used in the weapons drop operations across the border.

The investigation revealed the drones may have been launched from locations 2 km inside Pakistan and made to travel the distance of five kilometres at a height of 2,000 feet, and then dropped off the weapons after descending to 1200 ft. The payload was slung from the platform using Chinese mountaineering ropes.

The entire operation came to light after the discovery of the burnt drone, whose eight Chinese batteries were stripped off by the accused on instructions from across the border, reported Hindustan Times.

A senior Punjab Police official said, “It has also been revealed that such deliveries took place on four different dates, mostly between 9.30 pm and 10.30 pm with the drone making two sorties within an hour. The drones made around 10 visits.”

Punjab Chief Minister Amarinder Singh on Tuesday said the weapon deliveries by drones have added a “new and serious dimension on Pakistan's sinister designs”, and asked Union Home Minister Amit Shah to "handle" the problem.

Singh tweeted: “Recent incidents of Pakistan-origin drones dropping consignments of arms & ammunition is a new and serious dimension on Pakistan's sinister designs in aftermath of the abrogation of Article 370. Request @AmitShah ji to ensure that this drone problem is handled at the earliest.”

Drones are commonly used at border areas by the armed forces of both India and Pakistan to spy on each other as they are lightweight, easy to operate and relatively inexpensive.