Counter-terrorism police have arrested five men over concerns about a potential Islamist attack plot.

The arrests followed a joint investigation by MI5 and police, who conducted raids on Monday morning at residential addresses in London, Manchester and Peterborough.

The police side of the investigation is being led by Scotland Yard’s counter-terrorism command, with officers conducting searches of addresses in all three cities.

Investigators are understood to have been monitoring the men, aged 19 to 23, before their arrest.

Police said one man, 19, was arrested in Peterborough on suspicion of the commission, preparation or instigation of an act of terrorism. A 21-year-old man in Manchester and two men in north London, aged 22 and 23, were also arrested on suspicion of the same offence.

Another man, 19, was arrested in Peterborough on suspicion of encouraging terrorism.

A number of separate operations targeting suspected jihadist plots in Britain have failed to lead to charges being laid, and there have been claims of flawed intelligence.

The green light for the authorities to make the arrests on Monday came after a meeting of a committee of senior police and MI5 officials called an executive liaison group.

The decision to disrupt a suspected plot can be taken if counter-terrorism officials believe it too dangerous to allow suspects to remain free in the community, or if officials believe they have enough viable evidence to proceed through the justice system.

Police said there was no link between the arrests on Monday and November’s attack at London Bridge, nor to festivities planned across the country on Tuesday evening to mark the start of the new year.

“Searches are currently being carried out a number of addresses in Manchester, Peterborough and north London and the investigation is being led by detectives from the Met’s counter-terrorism command with support from counter-terrorism policing north-west and eastern region special operations unit colleagues,” the police said in a statement.

“The arrests were part of a pre-planned operation and there is not believed to be any imminent threat to the public in relation to this.

“The arrests are not linked to the attack at Fishmongers’ Hall in London on 29 November, nor the forthcoming New Year’s Eve celebrations.”

All five men remain in custody. Police have up to two weeks to charge or release the four arrested on suspicion of the commission, preparation or instigation of an act of terrorism.

The UK’s terrorism threat level was reduced in November from severe, meaning an attack is highly likely, to substantial, meaning an attack is likely.

The decision to reduce the level was made by the Joint Terrorism Analysis Centre (JTAC) on 4 November, before the London Bridge attack in which Usman Khan murdered Jack Merritt, 25, and Saskia Jones, 23 .

The majority of terrorist threats to the UK come from Islamists, but the far right has been described as the fastest growing menace. Authorities have disrupted 24 terror plots since March 2017, 16 inspired by radical Islamist ideology and eight by far-right ideology.

Counter-terrorism officials say the unrelentingly high tempo of terrorism activity prompted by the rise of Islamic State (Isis) decreased in 2019, but police and MI5 believe they foiled a dangerous plot in October. Officials have assessed that the threat of a mass casualty attack in the UK remains, particularly given reports of Isis regrouping following the loss of its territory in Iraq and Syria.



