Pakistan's army said on Saturday that four of its border patrol soldiers had been killed by a group operating from Iran, in an attack which was condemned by Prime Minister Shehbaz Sharif.
A separatist group, Baluch Liberation Army (BLA), which has previously been involved in attacks on Pakistani security forces and Chinese interests in the region, claimed responsibility in an emailed statement.
Insurgent ethnic Baluch nationalist groups, which operate on both sides of the border, have been fighting for decades for a greater share of regional resources.
The incident took place in the Kech district in southwestern Baluchistan province, which shares a long lawless border with Afghanistan and Iran.
"A group of terrorists operating from Iranian side attacked a routine border patrol of Pakistani security forces operating along Pakistan-Iran Border," the army said in a statement.
The Baluchistan province is rich in natural gas and minerals and also has the deep-water Gawadar port, which is being developed with Chinese money as part of Beijing's $65 billion "Belt and Road" investment in Pakistan.
The army said Pakistani authorities were making contact with Iran to seek ways of preventing such incidents in future.
Iranian officials were not immediately available to comment on Saturday, an annual holiday in Iran.
Iranian state media said Iran's embassy in Islamabad "condemned the terrorist attack in Baluchistan state and said terrorism is a common affliction of the two friendly and neighbouring countries."
(Reporting by Gul Yousafzai; Additional Reporting Saud Mehsud in Dera Ismail Khan, Pakistan and Dubai newsroom; Writing by Asif Shahzad, Editing by William Maclean, Giles Elgood and Alexander Smith)
