Iran hanged the leader of an armed Sunni group on Sunday, state television reported.
The hanging came after authorities exhausted legal requirements after months of interrogation and trial on charges of "being corrupt on earth" for waging a bloody campaign in Iran's southeast.
"Abdolmalek Rigi was hanged at dawn today ... he was convicted for many crimes like being behind many deadly attacks ... and killing dozens of innocent people," state television said.
Iran arrested Rigi, who was flying over the Persian Gulf en route from Dubai to Kyrgyzstan, in February, four months after his Jundollah (God's soldiers) group claimed a bombing which killed dozens of people, including senior officers of Iran's elite Revolutionary Guards.
Iran accuses Britain, the United States of supporting the group to create instability in southeast Iran. The three countries deny backing it.
A Tehran Revolutionary court sentenced Rigi to death and the Supreme Court upheld the sentence, Iran's semi-official Fars news agency said.
It said Rigi was executed inside Tehran's Evin prison in the presence of "the families of some of the victims".
"Abdolmalek Rigi's charges also included armed robbery, kidnapping, drug trafficking and formation and leading of the terrorist Jundollah group," Fars reported.
"Jundollah was linked to members of foreign intelligence services, including members from America and the Zionist regime's (Israel) intelligence services under the cover of NATO," the official IRNA news agency quoted a court statement as saying.
"The hanging showed Iran will not let its territory to be used by criminals...With the execution of Abdolmalek, the disgraceful stigma of our tribe was eliminated," Bashir Ahmad Rigi, the chief of Rigi's tribe, was quoted by IRNA as saying.
A leading lawmaker said Iran planned to file a lawsuit at relevant international courts against Britain and the United states for supporting Rigi.
"Based on Rigi's confessions, America and Britain were backing terrorist acts committed by him in Iran," said lawmaker Parviz Sorouri, the ILNA news agency reported.
Rigi's younger brother Abdulhamid was executed last month in Zahedan. He had been captured in Pakistan in 2008 and extradited to Iran.