Angry protesters occupied a governor's office in southeastern Iran on Tuesday, a day after at least two fuel smugglers were shot dead at the nearby border with Pakistan, according to Iranian media and online videos.
Iran, which has some of the lowest fuel prices in the world, has been fighting rampant smuggling to neighbouring countries, particularly in its impoverished Sistan-Baluchestan province - long the scene of clashes between security forces and separatist militants and drug smugglers.
Iranian officials have in the past tolerated limited smuggling as a source of income for a local population plagued by high unemployment, but have tightened controls recently, a resident told Reuters.
State TV quoted deputy provincial governor Mohammad Hadi Marashi as saying two people were killed by gunfire on the Pakistani side of the border.
But Pakistani border officials said protests broke out on Monday on the Iranian side of the frontier after Iranian forces fired at people involved in the illegal Iranian fuel trade.
Abdul Razaq Saloli, deputy commissioner of the border district of Panjgur, told Reuters that a body and an injured Pakistani were handed over to Pakistani border authorities by Iranian officials.
Saloli said the injured Pakistani man, identified as Shams Baloch, had reported that over 10 people had been killed and many others injured in the bout of shooting.
Protesters stormed the governor's office on Tuesday and set fire to a police car, according to videos posted on social media. Security forces were seen using tear gas to disperse the crowd. Reuters could not verify the authenticity of the footage.
Sana Ullah Baloch, a member of the provincial assembly in the neighbouring Pakistani region, said on Twitter that 12 Baluchi youths had been killed and urged Iran to investigate the incident and punish those guilty.