An Afghan border officer was killed and another wounded as both sides accused the other of opening fire first.
Clashes have erupted between Iranian border guards and Taliban forces, officials said, with the Afghan side confirming that one of their border officers was killed and another wounded.
Both sides accused the other of opening fire first during Sunday's exchange of fire.
"We have one killed and one wounded; the cause of the clash is not clear yet," the police spokesperson of the southern Afghan province of Nimroze, Bahram Haqmal, said.
"There was a clash between the border guards of the Islamic Republic of Iran and the Taliban forces," Meysam Barazandeh, governor of Iran's Hirmand county, was quoted as saying by the Farsnews agency.
He added that "the conflict was brief and has ended."
Farsnews reported that clashes took place on the Iranian side of the border, in the Shaghalak area of Hirmand country, in the southeastern province of Sistan-Baluchestan.
"A border violation by the Taliban took place today," Barazandeh said, adding that "our forces gave the necessary response", and that there "were no casualties" on the Iranian side.
Iran's Tasnim news agency said Taliban forces shot at some houses in the town of Dust Mohammad, which was followed by an exchange of fire "for several minutes."
Afghanistan blames Iranian guards
A statement issued by Afghanistan's Nimroz provincial information centre blamed Iranian border guards for the incident.
"Iranian border forces fired at a patrol of our border forces in Kang district of Nimroz province," the statement said.
"After that they (Iranian forces) fired in the area with light and heavy weapons. In this shooting, one of our border force personnel was martyred and another injured," it added.
Last month, Iran's foreign ministry reported the death of an Iranian border guard in an "incident" at a border crossing with Afghanistan, also in Sistan-Baluchestan.
READ MORE: What to expect for Taliban-Iran relations
Water rights issues
Water rights issues have also increased tensions between the neighbours.
In January, demonstrators in Sistan-Baluchestan rallied at a border crossing for a protest over water from the Helmand River.
Tehran has hosted millions of Afghan refugees for decades, but fresh arrivals have entered the country since the Taliban's return to power.