Indian security forces were working on Monday to defuse grenades in the final stages of an operation to secure a vast air base near the border with Pakistan, two days after a militant attack killed seven military personnel and wounded 22.

The attack, a rare targeting of an Indian military installation outside the disputed region of Kashmir, threatens to undermine a tentative thaw in relations with Pakistan.

A senior federal government official said two militants who were hiding in the administrative block of the base had been killed on Sunday, but authorities had yet to recover the bodies.