Iran has threatened to retaliate against the US if it designates its elite Islamic Revolutionary Guard Corps (IRGC) as a terrorist organisation.

Washington is reportedly expected to designate the IRGC as terrorists next week, marking the first time it has formally labelled another country’s military a terror group.

In response, a majority of Iranian parliamentarians said: “We will answer any action taken against this force with a reciprocal action.”

The statement was issued by 255 out of the 290 Iranian politicians, according to state news agency IRNA.

“So the leaders of America, who themselves are the creators and supporters of terrorists in the [Middle East] region, will regret this inappropriate and idiotic action,” it added.

The Islamic Republic of Iran 40 years on Show all 20 1 /20 The Islamic Republic of Iran 40 years on The Islamic Republic of Iran 40 years on Women praying during Ashura festivities in Yazd in February Jan Schneider The Islamic Republic of Iran 40 years on Cars cemented in at the Holy Defence Museum-Garden in Khorramshahr – in 1980 occupying Iraqi forces used such formations to deter paratrooper landings Jan Schneider The Islamic Republic of Iran 40 years on Women on the Si-o-se-pol bridge over the Zayanderude river in Esfahan Jan Schneider The Islamic Republic of Iran 40 years on Iranian tourists at Vank cathedral in the Armenian quarter in the city of Esfahan Jan Schneider The Islamic Republic of Iran 40 years on A reddened fountain in Yazd – a national motif recalling the countries ‘martyrs’ Pictures by Jan Schneider The Islamic Republic of Iran 40 years on Prayers before a list naming the fallen of the Iran-Iraq war in Tehran Jan Schneider The Islamic Republic of Iran 40 years on In a museum in central Tehran, a wax figure of Ayatollah Khomeini Jan Schneider The Islamic Republic of Iran 40 years on Carom billiards in Tehran Jan Schneider The Islamic Republic of Iran 40 years on Nearly two thirds of Iran’s population is under-30 Jan Schneider The Islamic Republic of Iran 40 years on Sanctions are exacerbating poverty Jan Schneider The Islamic Republic of Iran 40 years on Young people are adept at catching moments of freedom, such as this one in the capital Jan Schneider The Islamic Republic of Iran 40 years on At an art auction in Tehran, the wealthy turn out Jan Schneider The Islamic Republic of Iran 40 years on Propaganda murals are everywhere Jan Schneider The Islamic Republic of Iran 40 years on Tehranis love their outdoor spaces too Jan Schneider The Islamic Republic of Iran 40 years on The hypersaline waters of Lake Urmia are fast diminishing – Iran faces ecological catastrophe Jan Schneider The Islamic Republic of Iran 40 years on A martyr is depicted outside the huge Beheshte-e-Zahra cemetery in Tehran Jan Schneider The Islamic Republic of Iran 40 years on A guard naps outside Iran’s foremost tourist attraction – the ancient ruins of Persepolis Jan Schneider The Islamic Republic of Iran 40 years on Memorial to Iranian pilgrims who died during a stampede in Mecca 1987 Jan Schneider The Islamic Republic of Iran 40 years on The martyr fixation on display in the southern city of Shush Jan Schneider The Islamic Republic of Iran 40 years on Emamzadeh Saleh mosque in Shemiran, Tehran Jan Schneider

US secretary of state Mike Pompeo has advocated the change in US policy as part of the Trump administration’s tough posture towards Tehran.

In 2017, IRGC commander Mohammad Ali Jafari warned that if Donald Trump went ahead with the move “then the Revolutionary Guards will consider the American army to be like Islamic State [Isis] all around the world”.

The change in policy comes as Iran’s supreme leader Ayatollah Ali Khamenei urged Iraq to demand US troops leave “as soon as possible” during a visit by Iraqi prime minister Adel Abdul Mahdi.

Iran and the US have been competing for influence in Iraq since the US-led invasion that toppled dictator Saddam Hussein in 2003.

Some 5,200 troops are stationed in Iraq as part of a security agreement with the Iraqi government to advise, assist and support the country’s troops in the fight against Isis.

“You must make sure that the Americans withdraw their troops from Iraq as soon as possible because expelling them has become difficult whenever they have had a long military presence in a country,” Iran’s supreme leader was quoted as saying by state media.

Iran marks 40 years of the Islamic Republic

“The Iraqi government, parliament and current political activists in the country are undesirable for the Americans ... and they are plotting to remove them from Iraqi politics.”

Set up after the 1979 Islamic Revolution to protect the Shia cleric ruling system, the IRGC is Iran’s most powerful security organisation.

It controls large sectors of the Iranian economy and has huge influence in its political system.