Iran has arrested 27 people plotting attacks for the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group, including 10 who were arrested in a regional country, the intelligence ministry said.

"Intelligence agents succeeded in identifying and arresting a terrorist group linked to Daesh, who intended to conduct terrorist attacks in central provinces and religious cities," a ministry statement said on Monday, using the Arabic name for ISIL.

Ten of the suspects were arrested outside Iran "through intelligence-sharing with one of the intelligence services in the region," the statement said, without naming the country or giving further details.

ISIL attack in Iran: Why now and what will happen next?

Five of the 17 were due to carry out the attacks in Iran, and the other 12 were supporting them, the statement said.

Weapons and ammunition were also recovered during the arrests, and the suspects were reportedly trying to smuggle them into Iran inside home appliances.

Tehran suffered a rare and deadly twin attack on June 7, claimed by ISIL, when gunmen and suicide bombers attacked the parliament complex and the mausoleum of revolutionary founder Ayatollah Ruhollah Khomeini, killing 18 people.

Iranian security officials have since arrested dozens of suspects linked to the attack, and claim to have killed its chief planner.

On June 19, Iran also fired missiles into north-eastern Syria in retaliation, targeting an ISIL command base in Deir Az Zor province.

ISIL fighters have threatened more attacks against Iran's majority Shia population.

On Sunday, Iranian media said the Islamic Revolutionary Guard Corps had killed two people in clashes with a group of fighters in the north-west of the country, where shootouts with Iranian Kurdish fighters based in Iraq are common.