Indian authorities said on Monday they had chased away two more drones from a military area in the Jammu and Kashmir region, a day after a blast at an air base that was suspected to have been delivered by commercially available quadcopters.
Both drones flew away after troops fired on the craft around midnight, Lieutenant Colonel Devender Anand, a spokesman for the Indian military said in a statement.
"A major threat thwarted by the alertness and proactive approach of troops," he said. "The security forces are on high alert and the search operation is in progress."
Sunday's blast, blamed on separatist militants and which left two people injured, has caused concern in security circles as it could mark the first time that drones have been used in such an attack in India.
Vijay Kumar, a senior police official in the region, told Reuters the incident posed a new threat for security agencies.
"Certainty it is a big challenge but can be handled technologically," he said.
New Delhi has for decades been battling separatists in the disputed Himalayan region of Jammu and Kashmir, which has a Muslim majority population, blaming neighbouring Pakistan for supporting militants there. Islamabad denies involvement, saying it merely provides moral support for the Kashmiri cause.
While it is not clear who the drones were operated by in Sunday's attack, security officials told Reuters they were unlikely to have been launched from across the Pakistan border some 14 km away.
An Indian security official said authorities suspected that quadcopters were likely used for the attack, and were trying to track their flight paths since the GPS locations might have been pre-entered.
The official said initial reports showed the devices had a crude delivery mechanism to deliver a small payload of explosives.
Kashmir is claimed in full but ruled in part by nuclear armed neighbours India and Pakistan, although each control only parts of it. The region has been a flashpoint since the two nations gained independence from British rule in 1947.
Pakistan accuses India of rights violations in Kashmir. India says Pakistan supports militants in the part of the region that it controls and it has previously accused Pakistan of using drones to supply arms to militants in Kashmir. Both nations deny the accusations.
(Reporting by Fayaz Bukhari in Srinagar, additional reporting by Devjyot Ghoshal in New Delhi; Writing by Alasdair Pal; Editing by Alison Williams)
