Pakistan Foreign Minister Muhammad Ishaq Dar says eight civilians have died and 35 others have been injured following an attack on Pakistan and Pakistan-administered Kashmir by India.
Pakistan has confirmed three locations have been hit in what it described as a "cowardly attack".
India has not commented on the toll.
Pakistan has said Islamabad will respond "at a time and place of its choosing".
Reuters and AFP quote Indian army sources as saying three Indian civilians have been killed in military action by Pakistani troops in Indian-administered Kashmir.
Official confirmation is awaited.
Residents in Muzaffarabad in Pakistan-administered Kashmir told the BBC they were jolted awake by huge explosions.
Locals in Indian-administered Kashmir said they heard explosions near the Line of Control, the de-facto border between the two countries.
Relations between India and Pakistan - both nuclear-armed states - have declined sharply following a deadly militant attack on tourists in Kashmir last month.
Pakistan has denied involvement in the attacks, but Indian police say two of the four militants they suspect for the attack were Pakistani citizens.
A manhunt by the security forces is still under way.
Both India and Pakistan have announced a range of retaliatory measures against one another including closing borders and suspending a river water treaty.
Troops from both sides have also traded small arms fire.
Source: BBC
