BEIRUT (Reuters) - Iran fired missiles on Sunday into eastern Syria, aiming at the bases of militant groups it holds responsible for attacks in Tehran which left 18 dead last week, Iran’s Tasnim news agency reported.

A still image taken from a footage shot on June 18, 2017 and broadcasted on Iranian Television IRINN, purports to show missiles being fired from Iran into eastern Syria. IRINN/ via Reuters TV ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE CONTENT OF THIS VIDEO. NO ACCESS IRAN. NO ACCESS BBC PERSIAN, NO ACCESS MANOTO, NO ACCESS VOA PERSIAN DIGITAL, NO ACCESS VOA PERSIAN. NO RESALES. NO ARCHIVES IRAN OUT. NO COMMERCIAL OR EDITORIAL SALES IN IRAN. TPX IMAGES OF THE DAY

Iranian Revolutionary Guards launched the mid-range ground-to-ground missiles from western Iran into the Deir al Zour region of eastern Syria, killing a “large number” of terrorists and destroying their equipment and weapons, it said.

The missiles targeted the “headquarters and gathering centers of Takfiri terrorists supporting and building car bombs”, it said.

Reuters could not independently verify the report.

Military leaders and officials in Iran, a predominantly Shi’ite country, often refer to Sunni Muslim radicals as Takfiris.

The Revolutionary Guards are fighting in Syria against militant groups who oppose President Bashar al-Assad.

The attack last week, which included shootings and at least one suicide bombing, was on Iran’s parliament and the shrine of Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic.

“The spilling of any pure blood will not go unanswered,” the Revolutionary Guards said in the statement quoted by Tasnim.

Islamic State issued a statement claiming responsibility for the Tehran attack.

Senior Iranian officials, however, have pointed a finger at Saudi Arabia, Iran’s Sunni regional rival.