Iranian security forces have killed the mastermind behind the June 7 twin attacks in Tehran which claimed the lives of 17 people, the media reported on Sunday.
"The mastermind and main commander of the attacks on Parliament and the mausoleum of Ayatollah Khomeini was killed," Iran's Intelligence Minister Mahmud Alavi said in a televised programme on Saturday night.
Alavi said the operation was carried out by security forces on Saturday in collaboration with the secret services of neighbouring countries, reports Efe news.
The minister said the terrorist had fled the country after the attacks claimed by the Islamic State (IS) but did not reveal his identity or the country where he was killed.
In May, the Intelligence Ministry identified and neutralised almost one terror cell every day, but did not make the figures public to avoid spreading panic, Alavi added.
On Saturday, the authorities also announced the arrests of eight people in Alborz province, north of Tehran, who allegedly provided logistical support to the attackers.
With the latest arrests, the number of people detained since June 7 in relation to the attacks in the capital or extremist cells has passed 50.
The ministry previously said it had arrested 41 alleged IS members in the Kurdish provinces of Kermanshah, Kurdistan, West Azerbaijan and also in Tehran.
During the operations, the police seized documents, arms, explosives and ammunition from various terrorist hideouts.
The intelligence ministry on June 8 revealed the identities of the five attackers and said they had fought for the IS in Iraq and Syria.
This is the first time the Sunni extremist group carried out attacks in Shia-majority Iran.