"We remain in contact with both countries and what we believe is essential is that all exercise maximum restraint and avoid further escalation of tensions," EU spokeswoman Maja Kocijancic told reporters.

India said its warplanes attacked a militant camp where Pakistan-backed fighters were preparing suicide attacks on its cities, killing a "very large number" of militants from the Jaish-e-Mohammad (JeM) group.

Pakistani officials have confirmed Indian planes breached its airspace and dropped a payload over Balakot in the country's northwest, condemning it as "uncalled for aggression" but insisting there was no damage or casualties.

The escalation came after a February 14 suicide bombing claimed by JeM that killed 40 troops in Indian Kashmir, setting off a chain of threats and counter-warnings between the neighbours, who have fought three wars since independence from Britain in 1947.