Islamabad accuses Iran of violating its airspace in an attack against the armed group Jaish al-Adl and summons its ambassador.
Pakistan has said two children were killed and three others injured after neighboring Iran launched airstrikes that Islamabad described as a violation of its airspace.
Pakistan said it had summoned Tehran's top diplomat in Islamabad over the incident.
Social media accounts reported explosions in the mountainous province of Balochistan, where the two countries share a sparsely populated border nearly 1,000 kilometers (620 miles) long.
“This violation of Pakistan's sovereignty is completely unacceptable and may have serious consequences,” Pakistan's foreign ministry said in a statement.
He said Tuesday night's attack “led to the death of two innocent boys and injured three girls.”
Iran's state media earlier reported that Tehran had attacked two bases of the Jaish al-Adl armed group in Pakistan, and the IRNA news agency and state television said missiles and drones were used in the attacks. Press TV, the English arm of Iranian state television, attributed the attack to Iran's paramilitary Revolutionary Guard. There was no official comment from Tehran.
Jaish al-Adl, the “Army of Justice,” has been launching deadly attacks against Iranian border guards since at least 2013 and has previously claimed responsibility for bombings and kidnappings of border police.
Iran's Nournews newspaper, affiliated with the country's main security body, said the bases were in Balochistan province.
Pakistan's statement did not mention the location of the incident, but two Pakistani security officials told the Associated Press news agency that the Iranian strikes damaged a mosque in the Panjgur district of Balochistan, about 50 kilometers (30 miles) inside the border. The officials spoke on condition of anonymity because they were not authorized to speak to the media.
Tehran and Islamabad frequently accuse each other of allowing armed groups to operate from each other's territory.
“Pakistan has always said that terrorism is a common threat to all countries in the region that requires coordinated action,” the Ministry of External Affairs statement said.
“Such unilateral acts are not in accordance with good neighborly relations and can seriously undermine bilateral trust.”
On Monday, Iran fired missiles into northern Syria targeting the ISIL (ISIS) group and into Iraq at what it called an Israeli “spy headquarters” near the U.S. Consulate complex in the city of Erbil.
Iraq on Tuesday called the attacks, which killed several civilians, a “flagrant violation” of Iraq's sovereignty and recalled its ambassador in Tehran.
