Spies for hostile states including Iran will be locked up for longer under tougher sentencing laws.
Foreign agents guilty of committing national security crimes will no longer be automatically released ahead of serving their full prison sentences from Sunday.
This relates to offences including espionage, sabotage, or foreign interference.
Instead they will be thoroughly risk assessed by the Parole Board before being let out of prison after serving no less than two thirds of their sentence behind bars.
The Ministry of Justice said that once spies are released hey will be subject to rigorous supervision and some of the toughest monitoring conditions, such as being tagged, until the end of their term plus an extra year.
Justice Secretary David Lammy said: ‘Keeping the British people safe is our number one priority as a Government.
‘Those conspiring against this country should see this new measure as a clear warning. Public protection will always come first, and threatening activity by foreign powers will always be punished.’
Security Minister Dan Jarvis said: ‘States are deploying new hostile tactics on our streets, using proxies to do their dirty work and targeting our national infrastructure with cyber attacks.
Justice Secretary David Lammy said ‘those conspiring against this country should see this new measure as a clear warning’
‘Our police and security services have strong powers to defend and defeat these threats, but those responsible must face tougher consequences.
‘That is why we are introducing new laws so anyone compromising our national security for a foreign state will face longer behind bars.’
The tougher sentencing laws come after MI5 chief Sir Ken McCallum warned in October last year that Britain was in a ‘new era’ of threats, citing a 35 per cent increase in hostile state threat activity targeting Britain – with new plots and threats being detected ‘every day’.
He said Britain needs to ‘defend itself resolutely against threats‘, adding: ‘In this new era, with multiple overlapping threats on an unprecedented scale, we need to up our game.
‘We can’t rely solely on investigating and disruption. Together, we have to ensure that the UK is a hard target.
‘We want our adversaries to think twice before acting against us.’
Sir Ken warned of a ‘new era’ of unprecedented threats saying: ‘In 2025, MI5 is contending with more volume and more variety of threat, from terrorists and state actors than I’ve ever seen.’
He also spoke of ‘rising aggression on UK soil’, saying: ‘State threats are escalating. In the last year, we’ve seen a 35 per cent increase in the number of individuals we’re investigating for involvement in state threat activity.’
‘That means espionage, including against our Parliament, our universities, our critical infrastructure.
‘But now, states are also consistently descending into ugly methods MI5 is more used to seeing in our terrorism casework.
‘My teams are routinely uncovering attempts by state actors to commission surveillance, sabotage, arson, or physical violence, right here in the UK. We are dealing with these threats every day.’
MI5 has tracked more than 20 potentially lethal Iran backed plots in the last year.
