Iran and the United Kingdom have summoned each other’s top diplomats in a growing diplomatic dispute following the arrest of three Iranian men accused of espionage in the UK.

The three men — Mostafa Sepahvand, 39, Farhad Javadi Manesh, 44, and Shapoor Qalehali Khani Noori, 55 — appeared in a London court on Saturday, charged with conducting surveillance likely to aid a foreign intelligence service, reportedly Iran’s. They had all arrived in the UK between 2016 and 2022 and were granted temporary asylum.

According to the Metropolitan Police, the alleged spying activities took place between August 2024 and February 2025. Authorities believe the suspects were involved in identifying UK-based journalists critical of the Iranian regime, specifically those affiliated with Iran International, a Persian-language broadcaster banned and labelled as a terrorist entity by Tehran.

The arrests, made on 3 May, prompted a strong reaction from Iran’s state-run IRNA news agency, which reported that the UK’s charge d’affaires in Tehran had been summoned on Sunday to explain what Iran termed “unjustified” and “politically motivated” detentions.

In response, the UK’s Foreign Office summoned Iran’s ambassador to London on Monday. A statement from the Foreign Office asserted: “Protecting national security remains our top priority and Iran must be held accountable for its actions.”

Home Secretary Yvette Cooper echoed that message, saying, “We will not tolerate hostile state threats on British soil. We must continue to strengthen our powers to safeguard national security.”

A fourth man arrested on 9 May as part of the same investigation has since been released without charge.

The espionage case comes amid a broader counter-terrorism operation, which saw five other Iranian men arrested the same day in different cities across the UK — London, Swindon, Stockport, Rochdale, and Manchester. Four of those men, initially held on suspicion of preparing a terrorist act, have been released while the fifth remains on bail. Police say that investigation remains ongoing.

The incident has further strained already tense relations between the UK and Iran, with both countries trading diplomatic summonses over what is becoming an increasingly sensitive and complex case.