According to diplomatic protocols, any ambassador and diplomatic representative can travel to his country by presenting a note.

Macaire took part in a protest in front of Amir Kabir University in downtown Tehran on Saturday and was shortly detained.

He was summoned to the Iranian Foreign Ministry on Sunday for “unconventional behavior” inconsistent with his diplomatic status and being present in “students gathering”.

Before the British ambassador left Iran, he was reminded that the presence of foreign ambassadors in such gatherings is not in line with their responsibilities as a political representative of their country and it is contrary to the Vienna Convention on Diplomatic Relations of 1961.

UK envoy to Tehran Rob Macaire was temporarily was detained as an unidentified foreign national participating in an unlawful gathering held in front of Tehran Amir Kabir University on Saturday night.

Macaire, who was arrested while taking pictures of the protests, was immediately released after his identity was checked and approved by the police.

EU Foreign Policy Chief Josep Borrell in a Sunday tweet wrote, “Very concerned about the UK envoy being detained @HMATehran in Iran. Full respect of the Vienna convention is a must. The EU calls for de-escalation and space for diplomacy.”

A group of students had gathered inside the university to voice their protest after Iran announced the unintentional downing of a Ukrainian plane.

The General Staff of the Iranian Armed Forces announced on Saturday that the country’s air defense unintentionally shot down a Ukrainian passenger plane on January 8 amid the highest level of readiness because of a possible military attack by the US.

According to IRNA, Iranian Foreign Ministery has objected to the UK’s envoy act and is waiting for the police report on the details.

The UK Foreign Ministry has also objected to the detention of its ambassador to Tehran and called it against international law.