Three members of Iran's Islamic Revolutionary Guard Corps (IRGC) have been killed in a roadside bomb in Iranian-occupied Balochistan, according to Iranian media.
The men, who were travelling in a car at the time, were working on a "construction project" near the city of Saravan, in the southeastern "Sistan-Balochistan" province, which borders Pakistan and Afghanistan, according to Tasnim news agency.
It is the latest in a string of attacks by Sunni groups against Iranian authorities in the region, which is a hotbed of ethnic and religious separatism and opposition to the regime in Tehran.
In October, Iranian authorities hanged 16 Baloch rebels in retaliation for a militant attack which killed 14 Iranian border guards in the region.
The following month, Baloch rebels gunned down a public prosecutor and his driver in the city of Zabol in a revenge attack.
Baloch nationalist groups have waged a prolonged struggle for independence in Balochistan, which Iran has occupied since 1948, sometimes resorting to violent attacks in the face of severe oppression by authorities.
But regional unrest also has a religious aspect to it - most Baloch are Sunni Muslims, and analysts say the most recent upswing in violence is related to Shia Iran's role in propping-up the Allawite-led Assad regime in Syria as it battles Sunni rebels.
Iranian forces have played a key role in fighting the rebels. Apart from training and arming local and foreign pro-regime Shia and Allawite militias, Tehran has sent a significant number of operatives from the IRGC's elite "Qods Force" to Syria, to fight alongside regime forces.