Iranian state-run media say the British ambassador to Iran has left the country after being arrested and briefly detained.
The state-run IRNA news agency says Robert Macaire left after being given prior notice. The report did not elaborate.
Macaire had been held after attending a candlelight vigil Saturday in Tehran over Iran shooting down a Ukrainian jetliner, killing 176 people.
The vigil quickly turned into an anti-government protests and Macaire left shortly after, only to be arrested by police.
Iran's president warned Wednesday that European soldiers in the Mideast could be in danger after three nations challenged Tehran over breaking the limits of its nuclear deal.
Tehran's top diplomat meanwhile acknowledged that Iranians were lied to for days following the Islamic Republic's accidental shootdown of a Ukrainian jetliner that killed 176 people.
More From This Section
President Hassan Rouhani's remarks in a televised Cabinet meeting represent the first direct threat he's made to Europe as tensions remain high between Tehran and Washington over President Donald Trump withdrawing the US from the deal in May 2018.
Iranian Foreign Minister Mohammad Javad Zarif's admission, which came at a summit in New Delhi on Wednesday, represents the first time an Iranian official referred to earlier claims from Tehran that a technical malfunction downed the Ukraine International Airlines flight as a lie.
The shootdown has sparked days of angry protests in the country.
The current tensions between Iran and the US reached fever-pitch two weeks ago with the American drone strike in Baghdad that killed the powerful Revolutionary Guard Gen. Qassem Soleimani.
The general had led Iranian proxy forces abroad, including those blame for deadly roadside bomb attacks on US troops in Iraq.
Iran retaliated with a ballistic missile strike targeting Iraqi military bases housing US forces early last Wednesday, just before an anti-aircraft battery shot down the Ukrainian airliner taking off from Tehran's Imam Khomeini International Airport.
Amid all of this, Britain, France and Germany launched the so-called dispute mechanism pertaining to Iran's 2015 nuclear deal with world powers.
Speaking before his Cabinet, Rouhani showed a rarely seen level of anger in his wide-ranging remarks Wednesday.
"Today, the American soldier is in danger, tomorrow the European soldier could be in danger, Rouhani said.
He did not elaborate, though European forces have deployed alongside Americans in Iraq and Afghanistan.
France also maintains a naval base in Abu Dhabi, the capital of the United Arab Emirates, while Britian has opened a base in the island nation of Bahrain.
Rouhani separately criticized Europe's baseless words regarding the nuclear deal.
Iran had been holding out for Europe to offer a means by which Tehran could sell its oil abroad despite US sanctions.
However, a hoped-for trading mechanism for other goods hasn't taken hold and a French-pitched line of credit also hasn't materialised.
After Soleimani's killing, Iran announced it would no longer abide by any of the nuclear deal's limits, which had been designed to keep Tehran from having enough material to be able to build an atomic bomb if it chose.
However, Iran has said it will continue to allow the United Nations' nuclear watchdog access to its nuclear sites.
Rouhani on Wednesday also reiterated a longtime Iranian pledge that Tehran doesn't seek the bomb.
The European nations reluctantly triggered the accord's dispute mechanism on Tuesday to force Iran into discussions, starting the clock on a process that could result in the snapback of UN and EU sanctions on Iran.
The Europeans felt compelled to act, despite objections from Russia and China, because every violation of the deal reduces the so-called breakout time Iran needs to produce a nuclear bomb, Britain's Foreign Secretary Dominic Raab told parliament.
Under the deal's limits, experts believed Iran needed a year to be able to have enough material for a weapon.
Zarif, speaking in New Delhi at the Raisina Dialogue, blamed US ignorance and arrogance for fuelling mayhem in the Middle East.
However, he also acknowledged the anger Iranians felt over the plane shootdown.
In the last few nights, we've had people in the streets of Tehran demonstrating against the fact that they were lied to for a couple of days, Zarif said.
Zarif went onto praise Iran's military for being brave enough to claim responsibility early on."