At least 17 Iranian border guards have been killed in a clash with gunmen on the border with Pakistan, the official Iranian news agency Irna says.
The clashes took place on Friday night in a mountainous region outside Saravan, a border town in the south-east province of Sistan Baluchistan.
A number of guards were also wounded in the attack, reports said.
An unnamed official quoted by Irna blamed “bandits or rebels opposed to the Islamic republic”.
Iran lies on a major drug trafficking route between Afghanistan and Europe.
The population in this Sunni Muslim area complains of discrimination by Iran’s Shia establishment. An armed group, called Jundallah, has carried out a number of attacks against the state in recent years.
“We do not have exact details of the incident yet,” Tasnim news agency quoted Saravan’s member of parliament, Hedayatollah Mirmoradzehi, as saying.
“No group has claimed responsibility for the incident so far.”
“Since the venue of the operation is in a location that is geographically difficult of access, we have no exact information on whether any of the officers there were abducted or not,” he added.
The region has experienced repeated deadly clashes over previous years.
AFP news agency quotes officials as saying more than 4,000 police officers and soldiers have been killed in the past three decades in fighting with traffickers.