Starmer made the comments while speaking to the Jewish Chronicle newspaper during a visit Thursday to a London synagogue targeted by arsonists nearly a week ago.

The commitment comes after the European Union in January agreed to designate Tehran's Islamic Revolutionary Guard Corps (IRGC) a "terrorist organisation" over a deadly crackdown on mass protests.

"In relation to malign state actors more generally, proscription, we do need legislation in order to take necessary measures, and that is legislation that we're bringing forward as soon as we can," Starmer said when asked about the prospect of proscribing the Guards.

"We go into a new session (of parliament) in a few weeks' time and we'll bring that legislation forward," he added.

Jewish residents in northwest London remain on "high alert" after a spate of arson attacks on synagogues and community sites which began after the US-Israel strikes on Iran since February 28.

Starmer has said he is "increasingly concerned" about countries using proxies for criminal activity in the UK.

The IRGC is the ideological arm of Tehran's military and was created after the 1979 revolution to protect the clerical leadership.

The Guards control or own companies across the Iranian economy, including major strategic sectors.