Pakistani airstrikes in Afghanistan's Paktika province killed at least 46 people, most of whom were women and children, the Afghan Taliban said, adding they would retaliate.
Six people were also injured in the bombing at four locations in Afghanistan, Taliban deputy spokesman Hamdullah Fitrat said.
Afghanistan's foreign office said it had summoned Pakistan's head of mission in Kabul to deliver a formal protest note to Islamabad on the bombing, warning the diplomat of consequences of such actions.
"Afghanistan considers this brutal act a blatant violation of all international principles and an obvious act of aggression,” Enayatullah Khowrazmi, a spokesman for the Ministry of National Defence, said in a statement.
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Pakistan has yet to officially comment on the apparent airstrikes inside Afghanistan. However, Pakistani security officials anonymously told the AP news agency that the operation was aimed to dismantle a training facility and kill insurgents in the region.
The strikes came shortly after Mohammad Sadiq, Pakistan's special representative for Afghanistan, traveled to Kabul to discuss a range of issues.
Pakistan has seen innumerable militant attacks in recent years, with the latest attack taking place this weekend, when Pakistan's Taliban (TTP) killed 16 Pakistani soldiers in the country's northwest.
TTP pledges allegiances to the Afghan Taliban, but it is not directly a part of the group that rules Afghanistan.
The faction's stated aim is to impose Islamic religious law in Pakistan, similarly to the Taliban in Afghanistan.
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ftm/dj (Reuters, AP)