The UK’s ambassador to Iran Robert Macaire denied that he had taken part in a street protest in Tehran before he was detained by authorities.

Tweeting on Sunday morning, the senior diplomat said: “Thanks for the many goodwill messages. I can confirm I wasn’t taking part in any demonstrations! I went to an event advertised as a vigil for victims of the flight #PS752 tragedy. Normal to want to pay respects — some of the victims were British. I left after 5 mins when some started chanting.”

He added: “I was detained for half an hour after leaving the area. Arresting diplomats is, of course, illegal, in all countries.”

2/2

Detained half an hour after leaving the area. Arresting diplomats is of course illegal, in all countries. See comments by Foreign Secretary @DominicRaab. https://t.co/djpr99iSwI — Rob Macaire (@HMATehran) January 12, 2020

Media sources said on Saturday that Mr Macaire had been attending a vigil near Amir Kabir University for the 176 passengers and crew who died when the Revolutionary Guard “unintentionally” shot down the Ukrainian passenger aeroplane.

Iranian media claimed that the diplomat was taking part in protests, which was in breach of the Vienna convention which prohibits diplomats from interfering in the internal affairs of host countries.

But sources speaking to British media said that the diplomat had attended the vigil but left as soon as he realised it had evolved into a demonstration. He was then reportedly picked up by Iranian authorities while he was at a barber’s waiting to get a haircut before planning to return to the embassy. He was briefly detained before being released.

Britain warned Iran that it faced “pariah status” for its actions. Foreign minister Dominic Raab said in a statement on Saturday night:

“The arrest of our Ambassador in Tehran without grounds or explanation is a flagrant violation of international law. The Iranian government is at a cross-roads moment. It can continue its march towards pariah status with all the political and economic isolation that entails, or take steps to deescalate tensions and engage in a diplomatic path forwards.”

On Sunday, defence minister told Sky News that Iran’s actions were “totally unacceptable” and in breach of the Vienna convention.

He wasn't detained, but arrested as unknown foreigner in an illegal gathering. When police informed me a man's arrested who claims to be UK Amb, I said IMPOSSIBLE! only after my phone conversation w him I identified, out of big surprise, that it's him. 15 min later he was free. pic.twitter.com/VjuZxN1oTN — Seyed Abbas Araghchi (@araghchi) January 12, 2020

Iran’s deputy foreign minister Seyed Abbas Araghchi contradicted the British ambassador’s statement, inferring he was detained at the vigil, saying: “He wasn’t detained, but arrested as an unknown foreigner in an illegal gathering. When police informed me that a man’s arrested who claims to be the UK ambassador I said IMPOSSIBLE! Only after my phone conversation with him, I identified, out of a big surprise, that it’s him. Fifteen minutes later, he was free.”

The Iranian minister also maintained that the diplomat was arrested, rather than simply detained.