UK warns Iran poses 'unacceptable threat' to domestic security

British interior minister Yvette Cooper said Iran posed an "unacceptable threat" to the domestic security of the country after authorities charged three Iranian nationals under a national security law following a major counter-terrorism investigation.

"Let me be clear, we will not tolerate growing state backed threats on UK soil. The Iranian regime poses an unacceptable threat to our domestic security which cannot continue," Cooper told parliament on Monday.

"The UK will not accept any Iranian state threat activity in the UK."

The sharp statement comes after the arrests of Iranian nationals on UK soil this month in terrorism-related cases.

In two separate operations on May 3, eight men including seven Iranians were arrested by the British counter-terrorism police.

On Saturday, three of the Iranian nationals were charged with offences under the National Security Act, accused of acting on behalf of Iran’s intelligence service and carried out surveillance targeting Iran International journalists.

All three are accused of engaging in conduct likely to assist a foreign intelligence service between August 14, 2024 and February 16, 2025.

New counter-terror powers against IRGC

Meanwhile an advisor to the UK government on Monday recommended new powers targeting Iran’s Islamic Revolutionary Guard Corps, as calls for the IRGC’s proscription have grown following the spate of arrests.

The UK government’s independent reviewer of terrorism legislation Jonathan Hall published findings on Monday advising greater powers for ministers to designate people affiliated with the IRGC as terrorists.

Hall's report called for legislation proscribing public demonstrations of support for Iran's paramilitary organization such as displaying its insignia in public and recommended stiffer sentences for those aiding or benefiting from the IRGC.

The Revolutionary Guards cannot be blacklisted the same way non-state actors are, Hall argued, but he recommended its agents and supporters be targeted through a Statutory Alert and Liability Threat or Salt notice.

"It will allow the government to communicate decisive stigma at an international level for certain State and State-backed entities. Naming and shaming in a high-profile manner, accompanied by open reasons, can help address attempts at plausible deniability for serious harm caused to the UK or its allies," the report said.

"The Liability Threat Notice ... (puts the IRGC) on notice that its operations, and its minions and influence networks, are at greater risk of executive action, by way of arrest and prosecution, or deportation, or other forms of disruption, from UK authorities."

On Saturday, over 550 UK MPs and peers in an open letter urged the government to proscribe the IRGC as a terrorist group.