Nuclear-armed rivals India and Pakistan have exchanged gunfire across their heavily militarized de facto border in contested Kashmir since an April 22 attack that New Delhi blames on Islamabad, claims it rejects.

Troops are facing off along the 770-kilometre fortified Line of Control -- the route of a ceasefire line dating back to 1949 -- which ranges from icy outposts in high-altitude Himalayan mountains down to greener foothills in the south.

India and Pakistan have fought over the Muslim-majority region since their partition at the end of British rule in 1947.

Insurgents in Indian-run Kashmir have battled since 1989 seeking independence or a merger with Pakistan.

Both countries trade accusations of arming groups in each other's territory to cause instability.