At least 10 police officers were killed in a "terrorist attack" in an area of southeastern Iran long plagued by unrest, local media reported on Saturday.

They were killed during an attack on "police vehicles" in Sistan-Baluchistan province's Taftan county, the Mehr and Tasnim news agencies reported, without saying how it was carried out.

No group immediately claimed responsibility for the attack, which occurred some 1,200 kilometres (745 miles) southeast of the capital Tehran.

The official IRNA news agency, citing a police statement, reported the death of "10 personnel in two patrol units" in what it called an ambush.

Sistan-Baluchistan borders Pakistan and Afghanistan, and is one of the most impoverished provinces in the Islamic republic.

It is home to a large number of the Baluch minority, an ethnic group spread between Iran, Pakistan and Afghanistan who practise Sunni Islam in contrast to the country's predominantly Shiite population.

The province has experienced recurring clashes between Iranian security forces and rebels from the Baluch minority, radical Sunni groups and drug traffickers.

Saturday's attack was one of the deadliest attacks in the area in recent months.

In early October, at least six people, including police officers, were killed in the province in two separate attacks.

The Pakistan-based Sunni jihadist group Jaish al-Adl -- Army of Justice in Arabic -- claimed responsibility for the two attacks in a message on Telegram.

Formed in 2012 by Baluch separatists, the group is considered a "terrorist organisation" by both Iran and the United States.

Iran and Pakistan frequently accuse each other of allowing rebel groups to operate and launch attacks from their respective territories.

In mid-January, Iran carried out a strike in Pakistan and targeted the Jaish al-Adl headquarters, according to the Mehr agency.

Describing themselves as "soldiers of Allah", the group's members regularly call for "armed jihad" against the Islamic republic.