Iran has hanged two men for "terrorist acts" and another for murder and armed robbery, the judiciary's official Mizan news agency said.
The three were executed in the early morning of January 3 in the southeastern Sistan-Baluchistan province, Mizan reported.
Two were identified as Hassan Dehvari and Elias Qalandarzehi, who were arrested in April 2014 after being found with "a large amount of explosives" and weapons, the report said.
The pair were convicted of the abduction, bombing, murder of security forces and civilians, and of working with the Sunni Muslim extremist group Jaish al-Adl (Army of Justice), Iranian media reported.
The U.S.-based Human Rights Activists News Agency (HRANA) said the two had been tortured in detention.
Dehvari and Qalandarzehi were also arrested in possession of documents from Jaish al-Adl on "how to make bombs" as well as "takfiri fatwas", terms used by Iranian authorities to refer to religious decrees issued by Sunni extremists.
Jaish al-Adl has reportedly carried out several high-profile bombings and abductions in Iran in recent years.
In February 2019, 27 members of Iran's Islamic Revolutionary Guards Corps (IRGC) were killed in a suicide attack in Sistan-Baluchistan claimed by the group.
Sistan-Baluchistan is a volatile area near Iran's borders with Pakistan and Afghanistan where militant groups and drug smugglers frequently operate.
The third man executed was named as Omid Mahmudzehi. He was convicted of armed robbery and the murder of civilians, Mizan said.
Iran is one of the world's leading executioners. Amnesty International said in April that at least 251 people were executed by Iranian authorities in 2019.
Iran is also among a handful of countries that execute juvenile offenders.