A suicide bomb that killed four policeman in a city in Iran has been claimed by a Sunni militant group.

The attack on a police headquarters in the southeastern port of Chabahar was claimed by a faction rooted in Iran’s ethnic Baluch minority.

The bomb also wounded 35 people, according to local media. Rahmdel Bameri, a provincial official, said a suicide attacker in a vehicle loaded with explosives drove up to the building. Police officers blocked the vehicle and started firing at the driver, who then detonated his explosives, he said. Such attacks in Iran are rare.

A group called Ansar al-Fuqran issued a statement claiming responsibility for the attack, lauding it as “a severe blow to the regime’s security forces”.

The statement said: “A dedicated Baluch jihadi son targeted the local police headquarters in Chabahar in an effort to combat the regime, resulting in the death and injury of a large number of regime officers. The Iranian Ansar al-Fuqran Group declares that it has taken to a military action through its warriors as a result of the lack of opportunity for civic activity.”

Iran immediately blamed outside powers for the attack and vowed retribution. “Foreign-backed terrorists kill and wound innocents in Chabahar,” Iran’s foreign minister, Mohammad Javad Zarif, tweeted. “As we’ve made clear in the past, such crimes won’t go unpunished.”

Alluding to the 2010 capture of Baluchi militants on a plane flying from the United Arab Emirates, he wrote: “Mark my words. Iran will bring terrorists and their masters to justice.”

Revolutionary Guard spokesperson Brigadier General Ramezan Sharif was quoted as saying: “Terrorist groups are mostly linked to foreign intelligence services such as Saudi Arabia. These terrorist attacks will receive crushing responses.”

The bombing targeted a port city that is the centrepiece of planned economic expansion plans involving India and Afghanistan. Chabahar is exempt from Trump administration sanctions targeting Iran.

It was the second major terrorist attack targeting Iran in less than three months, following a 22 September attack on a military parade by gunmen disguised as a soldiers in the country’s southwest.

Chabahar, near Iran’s border with Pakistan on the Sea of Oman, is home to a recently-built port and is an economic free zone for the country.

A suicide car bomber killed at least two outside the police headquarters in the port city of Chabahar in restive southeastern Iran on 6 December, 2018 (AFP/Getty Images)

A co-ordinated Isis attack last year on parliament and the shrine of Ayatollah Ruhollah Khomeini, the leader of Iran’s 1979 Islamic Revolution, killed at least 18 people and wounded more than 50 in the capital.