Hardline former top nuclear negotiator Saeed Jalili was on Thursday appointed to Iran's top political arbitration body, the Expediency Council, state television reported.
The appointment was made by Iran's supreme leader Ayatollah Ali Khamenei, to whom the council provides advice on different national issues.
It comprises high-ranking religious and political figures and former government officials, and is also tasked with resolving legislative issues between the parliament and the Guardians Council, which interprets the constitution.
Under former president Mahmoud Ahmadinejad who now sits on the council, Jalili was secretary of the Supreme National Security Council (SNSC).
New President Hassan Rowhani on Thursday replaced Jalili with decorated admiral Ali Shamkhani, who served as defence minister under two reformist administrations.
Signup to our newsletter and follow us on Facebook and Twitter!
Jalili ran unsuccessfully in the June 14 elections against Rowhani, who won a surprise victory.
He campaigned on the strength of having been Iran's point-man in talks with the so-called P5+1 group of world powers on Tehran's controversial nuclear ambitions since 2007, which have never achieved a breakthrough.
But his performance in the talks, and what was described as an inability to make concessions, were criticised during the presidential campaign.
The television also said Khamenei had chosen Shamkhani as his special representative to the council for the next three years, replacing Rowhani, who had been one of the supreme leader's two representative since 1989.
Until now, the SNSC has been heavily involved in Iran's nuclear talks, but its active role is expected to be diminished after Rowhani charged the foreign ministry last week with taking the lead on negotiations.
The SNCS is tasked with dictating defence and security policies and for marshalling Iran's resources to confront domestic and foreign threats.