Hafte Tir bombing

On 28 June 1981 (7 Tir 1360 (, ) in the Iranian calendar), a powerful bomb went off at the headquarters of Islamic Republican Party (IRP) in Tehran, while a meeting of party leaders was in progress. Seventy-three leading officials of the Islamic Republic of Iran were killed, including Chief Justice Ayatollah Mohammad Beheshti the second-most powerful figure in the Iranian Revolution (after Ayatollah Ruhollah Khomeini). The Iranian government first blamed SAVAK and the Iraqi regime. Two days later, the People's Mujahedin of Iran was accused by Khomeini.
Bombing.
On 28 June 1981 the Hafte tir bombing occurred killing the chief justice and party secretary Ayatollah Mohammad Beheshti, four cabinet ministers (health, transport, telecommunications and energy ministers), twenty-seven members of the Majlis, including Mohammad Montazeri, and several other government officials.
Immediate aftermath.
Khomeini accused the PMOI to be responsible and, according to BBC journalist Baqer Moin, the Mujahedin were "generally perceived as the culprits" for the bombing in Iran. The Mujahedin never publicly confirmed or denied any responsibility for the deed, but stated the attack was ‘a natural and necessary reaction to the regime's atrocities.’ The bomber was identified as a young student and Mujahedin operative by the name of Mohammad Reza Kolahi, who had secured a job in the building disguised as a sound engineer.
Iranian judicial proceedings, views and commemoration.
Assassinations of "leading officials and active supporters of the regime by the Mujahedin were to continue for the next year or two," though they failed to overthrow the government.
According to Tasnim, it is not possible that MEK to be fully responsible for the incident, and the bomb had been transmitted to Iran or built by military technicians in the country, with the help of Western and Israeli spy services. In other words, the United States and Israel, with the sophisticated technology of that day, designed the bomb and plan of operation then presented the bomb and plan to MEK for operating.
To commemorate the event several public places in Iran including major squares in Tehran and other cities are named “Hafte Tir”.
Analysis.
According to Ervand Abrahamian, "whatever the truth, the Islamic Republic used the incident to wage war on the Left opposition in general and the Mojahedin in particular."
According to Kenneth Katzman, "there has been much speculation among academics and observers that these bombings may have actually been planned by senior IRP leaders, to rid themselves of rivals within the IRP."
The 2006 U.S. department of state Country report says that "In 1981, the MEK detonated bombs in the head office of the Islamic Republic Party and the Premier's office, killing some 70 high-ranking Iranian officials."
Assassination of Mohammad-Reza Kolahi.
Mohammad-Reza Kolahi, accused of being involved in the bombing, was murdered in 2015. Kolahi was living in the Netherlands under false identity of Ali Motamed () as a refugee, was married to an Afghan woman and had a 17-year-old son.<ref name="RFE/RL"></ref> Iran denied it was involved in the murder.