"An Indian mortar shell hit a house in Nakyal sector along the Line of Control that killed a mother, daughter and son while three others were injured," local disaster management authority official Shariq Tariq told AFP.

New Delhi and Islamabad regularly accuse each other of firing across the heavily-militarised de facto border in Kashmir, called the Line of Control.

Tariq said another woman was killed and seven others injured in shelling elsewhere in Nakyal. Local police official Irfan Saleem confirmed the incident.

The deaths came as India said Tuesday it had launched air strikes against militant camps in Pakistan's territory, following a suicide attack that killed 40 Indian soldiers in Kashmir earlier this month.

Pakistan denied India's claim that the attack had inflicted major damage and casualties on militants responsible for the February 14 bombing as "reckless and fictitious", and said it would respond in due course.

The purported attack would be India's first use of air strikes against Pakistan since 1971, when the two went to war over Bangladesh's independence.

The incursion across the ceasefire line that divides Kashmir came after India threatened retaliation over the suicide bombing this month that was claimed by the Pakistan-based Jaish-e-Mohammad (JeM) group.

The escalation has triggered international alarm, with China and the European Union calling for both sides to show restraint.

Kashmir has been divided between Pakistan and India since the end of British colonial rule over the subcontinent in 1947. Both sides claim the territory in full.

Firing across the Line of Control has killed and wounded dozens of soldiers and civilians on both sides in recent years.