Released for the first time on Tuesday, the top secret papers dating back to 1953 make clear Washington's concern over failing to successfully oust the government of Muhammad Mossadegh.

The papers provide proof of the widely-known US-British policy of destabilising an Iranian government that resisted attempts to allow the West control over its oil resources.

The Mossadegh government was toppled on 19 August 1953 in a coup led by US-backed general Fadl Allah Zahedi - who allowed pro-American Shah Reza Pahlavi to return from exile.

Contingency plan

However, the US State Department and the National Security Council documents show that the White House had called for the creation an anti-communist guerrilla force in the south of Iran.
  
President Dwight Eisenhower was seriously concerned that its planned coup could go awry, and Iranian communists from the Tudeh Party would capitalise on instability and the unravelling economy to seize power.
  
To counter that possibility, then-undersecretary of state Walter Smith made preparations for unleashing a guerrilla campaign targeting Tudeh members and other Iranian politicians.
  
In his memorandum dated 20 May 1953, Smith noted that the CIA had reached an agreement with Qashqai tribal leaders in southern Iran to establish a clandestine safe haven from which US-funded guerrillas and intelligence agents could operate.