Hardliner Iranian websites on Saturday evening reported that the British ambassador in Tehran, Robert Macaire, was arrested by security forces "amongst protesters". According to these reports, the Iranian foreign ministry intervened and Macaire was released after a few hours.
Tasnim News Agency affiliated with Revolutionary Guard claimed that the British ambassador who was arrested for "instigating and organizing suspicious activities in front of Amir Kabir University" where a large protest rally was underway will be summoned to the foreign ministry tomorrow for further investigation. Tasnim also claimed that a "shop opposite Amir Kabir University was the main place" for the British ambassador's purported activities.
Criticizing the foreign ministry for intervening to free the British ambassador a hardliner Twitter user tweeted: "Do we have a foreign ministry or a British Interests Section?" and posted a photo of the British ambassador allegedly showing Macaire after being detained.
Rahbord-e Moaser, a hardliner website, said the reason for Macaire's arrest was "instigating the crowd and taking photos of the protest".
According to a statement released on the website of the Foreign and Commonwealth Office, Foreign Secretary Dominic Raab said: 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.
In 2009 during the unrest that followed a disputed election, Iran alleged that Iranian employees of the British embassy had played a role in the post-election protests and charged an Iranian employee of the embassy with espionage and acting against national security.
The Iranian Supreme Leader Ali Khamenei blamed Britain for the unrest in his first speech after the announcement of the election results.
In November 2011 hardliner mobs that demanded the expulsion of the ambassador stormed the embassy and ransacked its offices. The embassy closed and British diplomats went back home until diplomatic relations were re-established and the embassy opened again in 2015.