At least 28 civilians were killed after Pakistan launched air strikes and sent ground troops into Afghan provinces along its border on Sunday, the United Nations Afghan mission has said.
A further 49 were injured and women and children were among the victims, according to Unama.
Afghanistan’s Taliban government said civilian homes were hit and described the attack as a “cowardly act” and an “atrocity”.
Meanwhile, Pakistan said it had targeted militant hideouts in Afghanistan’s Paktia, Paktika and Kunar provinces.
The neighbouring countries agreed to a ceasefire last October following weeks of deadly clashes – an agreement that has since fallen apart.
Casualties were concentrated in Mandokhail, a village in the Paktia province, according to Taliban officials.
Adam Khan, 63, told AFP news agency he “cannot put into words the condition of the children I saw at the hospital, or the screams of their parents and siblings”.
Those killed in one of the strikes included “children, elderly people and women” sleeping in a house, he said.
Afghanistan’s Taliban government put the civilian death toll at 36 and said more than 160 had been injured.
Pakistan’s information minister Attaullah Tarar said 29 militants had been killed in an operation responding to “recent terrorist attacks against innocent people”.
The BBC has not independently confirmed figures from either side.
The attacks come a day after three members of the Sindh Rangers, a Pakistani paramilitary force, were killed at their headquarters in Karachi, according to Pakistan’s military. Three militants also died in the suicide attack, and Pakistani officials said they had arrested a fourth, who was an Afghan.
Jamaat-ul-Ahrar, a splinter faction of the TTP, claimed responsibility for Saturday’s attack.
Both the TTP, also known as the Pakistan Taliban, and Jamaat-ul-Ahrar are banned in Pakistan, and by the UN, because of their involvement in past attacks.
