Intelligence agencies are searching for members of a secret Iranian network of assassins under orders to attack Jewish, Israeli and Western targets in Turkey.
According to intelligence sources, the organisation behind the attack is known as Unit 400, a secret part of the al Quds Brigade, which falls under the direct command of Ayatollah Ali Khamenei, Iran's Supreme Leader.
"Unit 400 of the Qods Force has been developing in the last few months a standing operating procedure for carrying out an attack in Turkey against western targets as well as Israeli and Jewish. It is our firm assessment that these procedures are in a very advanced stage, and that the intention is to act on the plans very soon," an intelligence source told Sky News.
There is also evidence that Unit 400 has been given instructions to carry out more frequent and more daring 'terror' attacks around the world as a demonstration of 'Iran's asymmetric power' - in the face of the growing threat of Israeli or American air strikes on its alleged nuclear weapons programme, the sources said.
The sources named a senior officer in Unit 400 as being a key Iranian agent who "has been working up plans for potential attacks in European countries".
"Unit 400 is a top-secret "special ops" unit within the elite overseas wing of the Islamic Revolutionary Guard Corps Qods Force (IRGC-QF). It plans and carries out terror attacks on external targets, and provides material support to foreign militia groups, at the direct behest of the Supreme Leader Ali Khamenei. This is in accordance with the regime's core strategic considerations about how best to challenge perceived enemies in Israel and the west - through asymmetric warfare - and to cope with mounting international pressure over its nuclear programme," a secret study by a foreign intelligence agency said.
Several international intelligence sources confirmed that Ali Khamenei controlled the Quds Force through his close ally Qassem Suleiman.
"He runs the whole thing - directly. [Mahmoud] Ahmedinajad [the Iranian president] makes all the noise and gets the attention but it's the Supreme Leader who is in charge of what is going on especially when it comes to international operations," said a senior intelligence official.
Turkey has been the scene of at least two attempts against Israeli targets in recent years - in 2009, 2010, and in 2011 when six Turkish civilians were injured during an attack blamed on Unit 400 on the Israeli consul in Istanbul.
Unit 400 is also identified in the document as being behind the failed plot to assassinate the Saudi Ambassador to Washington using Mexican drug mafia last year.
The commanders of Unit 400 have been identified as Hamed Abdellahi and Majid Alavi who is a former deputy minister in Iran's Ministry of Intelligence and Security.
"[The] Supreme Leader makes a decision to conduct an attack, the Unit activates a cell to perform it and recruits foreign agents as required… Training is sometimes given in Iran, as was the case prior to an attempted attack on the Israeli consul in Istanbul in 2011, and additional countries in the Middle East and Europe are used in order to blur Iran's connection to the attack," an intelligence document obtained by Sky says.
"The overall picture is one of an organisation which reaches out across the globe to commit carefully planned terror attacks of its own accord, as well as to arm proxy groups that will do so on its behest."
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