The Indian mission has also lodged a strong protest with Pakistan over the incident through a note verbale which is a diplomatic communique, people familiar with the development said.

The incident came to light amid growing concerns in the security establishment in India after explosives-laden drones were used to carry out an attack on the Jammu Air Force station on June 27.

“A drone was spotted over the premises of the Indian High Commission in Islamabad on June 26. This has been taken up officially with the government of Pakistan. We expect Pakistan to investigate the incident and prevent recurrence of such breach of security,” External Affairs Ministry Spokesperson Arindam Bagchi said at a media briefing. It is learnt that the drone was sighted within the complex when an event was being held at the mission.

Asked about the drone attack on Jammu airbase, Bagchi declined to comment, and only said that the investigation into it is in progress.