Source: Deutsche Welle [German state media]
“Iran’s Ministry of Foreign Affairs summoned a British envoy in Tehran over the arrest of Iranian nationals in the United Kingdom on charges of espionage, state media reported on Monday. ‘Following the unjustified arrest of a number of Iranian nationals in the UK … the British charge d’affaires in Tehran was summoned on Sunday,’ Iran’s IRNA news agency said. … British police held 7 Iranians earlier this month in two separate operations. Of those, three men appeared in a London court on Saturday after being charged with engaging in conduct likely to assist a foreign intelligence service, that being Iran in their case. … the other four men — who were arrested on suspicion of preparation of a terrorist act — have been released from custody but they still face a probe.”
https://www.dw.com/en/iran-summons-british-diplomat-over-arrest-of-nationals/a-72587364