US officials acknowledged that attacks on Iranian nuclear scientists in Iran are being carried out by an Iranian dissident group financed, trained and armed by Israel’s intelligence agency, Mossad, NBC news reported on Thursday.

The report confirmed Iran’s suspicions about the Mossad aiding the group, the People’s Mujahedin of Iran, which the US has long declared as a terrorist organisation. The group, also known as MEK, MKO and PMI, has been accused of killing American servicemen and contractors in the 1970s and supporting the takeover of the US Embassy in Tehran before distancing themselves from the Iranian ‘mullahs’ in 1980.

The US officials, speaking on condition of anonymity, said the Obama administration is aware of the assassination campaign but has no direct involvement.

Two senior officials said, “All your inclinations are correct,” while a third official would not confirm or deny the relationship, saying only, “It hasn’t been clearly confirmed yet.” All the officials denied any US involvement in the assassinations.

Five Iranian scientists have been killed since the target killings first began in 2007, coinciding to when the US-Iran rift inflamed over the latter’s nuclear program and the Western superpower’s apprehensions against it. The US continues to impose sanctions on Iran, restricting its trading and commercial activities with other countries, including the Iran-Pakistan pipeline project.

The killed scientists include Particle physicist Masoud Alimohammadi (2010), Majid Shahriari, nuclear scientist (2010), Fereydoun Abbasi-Davani (2010), Darioush Rezaeinejad (2011) and Mostafa Ahmadi Roshan (2012).

The modus operandi of the attacks was usually very dramatic, with motorcycle-borne assailants often attaching small magnetic bombs to the exterior of the victims’ cars. The group has also attacked missile research and development sites.

Mohammad Javad Larijani, a senior aide to Iran’s supreme leader Ayatollah Ali Khamenei, describes the  relationship between the Mossad, and MEK as very close.

“The relation is very intricate and close,” said Mohammad Javad Larijani, a senior aide to Ayatollah Ali Khamenei, Iran’s supreme leader, speaking of the MEK and Israel.  “They (Israelis) are paying … the Mujahedin. Some of their (MEK) agents … (are) providing Israel with information.  And they recruit and also manage logistical support.”

Larijani added that the Mossad was providing training to MEK in Israel, also revealing that Iran had learnt about the alleged links from an interrogation of an assassin who failed to carry out an attack in late 2010 and the materials found on him.

“Israel does not have direct access to our society. Mujahedin, being Iranian and being part of Iranian society, they have … a good number of … places to get into the touch with people. So I think they are working hand-to-hand very close.  And we do have very concrete documents.”

“This is an Israeli plot.  A dirty plot,” Larijani added angrily. He also claimed the assassinations are not having an effect on the program and have only made scientists more resolute in carrying out their mission.

Ronen Bergman, an Israeli commentator and author of Israel’s Secret War with Iran, thought otherwise, saying that, “Scientists leaving the project, afraid that they are going to be next on the assassination list, and say, ‘We don’t want this.  Indeed, we get good money, we are promoted, we are honored by everybody, but we might get killed.  It isn’t worth it.  Maybe we should go back to teach … in a university.”

Iranian officials initially have also added the CIA to the list, after the January 11, 2012, bombing in Tehran that killed Roshan. The state news agency IRNA reported that Iran’s Foreign Ministry had sent a diplomatic letter to the US claiming to have “evidence and reliable information” that the CIA provided “guidance, support and planning” to assassins directly involved in the attack.

US Secretary of State Hillary Clinton  immediately denied any connection to the killings. “I want to categorically deny any United States involvement in any kind of act of violence inside Iran,” Clinton told reporters on the day of the attack.

Israel’s Foreign Ministry declined to comment, “As long as we can’t see all the evidence being claimed by NBC, the Foreign Ministry won’t react to every gossip and report being published worldwide.”

While the MEK pointed to a statement calling the allegations “absolutely false.”