The frontier between arch-foes India and Pakistan was peaceful and had the "first calm night in recent days," the Indian army said Monday after a surprise weekend ceasefire.

The truce was agreed to on Saturday after four days of missile, drone and artillery attacks between the two countries, which killed at least 60 people and sent thousands fleeing.

It was the worst violence since the nuclear-armed rivals' last open conflict in 1999 and sent global shudders that it could spiral into full-blown war.