The UN mission in Afghanistan said Monday it had received "credible reports" that at least 13 civilians were killed and seven others injured in overnight Pakistani airstrikes inside Afghanistan.
The UN mission said the casualties, including women and children, were reported in Nangarhar province.
In Paktika province, the strikes hit a madrassa and partially damaged a mosque and a house, the UN mission said, adding that no civilian casualties were immediately reported there.
The UN mission called on both sides to end hostilities and take all measures to protect civilians.
Pakistani jets carried out airstrikes in eastern and southeastern Afghanistan early Sunday, targeting what Islamabad described as militant hideouts.
Afghan officials claimed civilians were killed in the strikes and vowed retaliation.
Pakistan's deputy interior minister, Talal Chaudhry, told local broadcaster Geo News that at least 70 "terrorists" were killed, citing preliminary reports.
Enayatullah Khwarazmi, a spokesman for Afghanistan's Defense Ministry, and government spokesman Zabihullah Mujahid claimed the strikes killed and wounded dozens of women and children.
Pakistan has seen a surge in militant violence in recent years, much of it blamed on the Pakistani Taliban and outlawed Baloch separatist groups.
Islamabad accuses the Pakistani Taliban of operating from Afghanistan, a charge that Taliban-led government in Kabul has repeatedly denied.
Relations between the two neighbors have remained tense since deadly clashes last October. A ceasefire mediated by Qatar largely held, but subsequent talks in Istanbul failed to produce a formal agreement.
