Iranian authorities say they have arrested 41 suspects in connection with this week's attacks in Tehran, the interior ministry said.
This is the highest number of arrests related to a terror attack in Iran, in recent years.
Islamic State claimed responsibility for the suicide bombings and gun attacks on parliament and the mausoleum of the Islamic Republic's founder, Ayatollah Khomeini, on Wednesday, that killed 17 people.
"With the help of security forces and families of the suspects, 41 people linked to the attacks and to Daesh (Islamic State) have been arrested in different provinces," state TV quoted the interior ministry as saying. "Lots of documents and weaponry have been seized as well," it added.
The Iranian leadership, including the Supreme Leader, ayatollah Ali Khamenei have accused the U.S. and Saudi Arabia in having a hand in the attacks. A letter has also been sent to the U.N. Security Council.
Iranian intelligence has blamed Sunni extremist “Takfiri” groups for having recruited the Iranians who conducted the attacks. Iranian authorities usually use the term Takfiri to mean Sunni extremists allegedly linked to Saudi Arabia.