TEHRAN: Iran has called in the Swiss charge d'affaires, who looks after US interests, to protest against comments by Secretary of State Rex Tillerson backing "peaceful transition" in the Islamic republic.
The administration of President Donald Trump has taken an increasingly hawkish position towards Iran since taking office in January but Tillerson's testimony to a Congressional committee last week appeared to be the first expression of support for a change of government.
"The Swiss charge d'affaires was summoned to the foreign ministry to be a handed a strong protest from the Islamic Republic of Iran against the comments by the US secretary of state.... which were contrary to international law and the UN charter," ministry spokesman Bahram Ghassemi told Iranian media.
Alongside yesterday's summoning of the Swiss envoy, Iran also sent a protest letter to UN chief Antonio Guterres, the ISNA news agency reported.
In last Wednesday's testimony to the House Foreign Affairs Committee, Tillerson accused Iran of seeking "hegemony" in the Middle East at the expense of US allies like Saudi Arabia.
"Our policy towards Iran is to push back on this hegemony... and to work toward support of those elements inside of Iran that would lead to a peaceful transition of that government," the US top diplomat said.
"Those elements are there certainly, as we know," he added, without elaborating on the groups he was referring to.
Iran was, with North Korea and Saddam Hussein's Iraq, part of the "axis of evil" that the George W. Bush administration earmarked for "regime change" after it took office in 2001.
But when Saddam's ouster in the US-led invasion of 2003 triggered a deadly insurgency that continues to this day, the policy fell out of favour.
In his testimony, Tillerson also raised the possibility of imposing sanctions on the whole of the Islamic Revolutionary Guard Corps, Iran's main military force and a major player in the country's economy.
Currently, Washington has only blacklisted the Guards' foreign operations arm -- the Quds Force -- and some individual commanders.
"We continually review the merits, both from the standpoint of diplomatic but also international consequences, of designating the Iranian Revolutionary Guard in its entirety as a terrorist organisation," Tillerson said.
The Guards have played a major role in training Shiite militias in Iraq that are a significant force in the fightback against the Islamic State group, and have also trained thousands of "volunteers" to battle alongside President Bashar al-Assad's forces in Syria.
The United States has had no diplomatic relations with Iran since the aftermath of the Islamic revolution of 1979 and its interests are looked after by Switzerland.