A 31-year-old Iranian man has been arrested as part of a counter-terror investigation in which three other Iranians were detained at the weekend.
The suspect was taken into custody at an address in northwest London on Friday morning, police said.
It comes after three other men of the same nationality, aged 39, 44 and 55, were arrested at addresses in the capital on Saturday, 3 May, as part of the same investigation.
Warrants of further detention have been sought and obtained for the trio today, meaning they can be held until Saturday, 17 May, police said.
All four men are being held under the National Security Act 2023.
In a separate operation on Saturday, counter-terror officers arrested five men – also Iranian nationals – during raids at various locations in Greater Manchester, London and Swindon.
The Met said those arrests related to a “suspected plot to target a specific premises”, which Sky News understands to be the Israeli embassy in London.
Police said the two counter-terror operations were not connected.
All the suspects remain in police custody.
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On Thursday, the Iranian government denied any involvement.
In a statement posted on X, Iranian foreign minister Seyed Abbas Araghchi said: “We are seeing stories in the media that Iranian nationals are allegedly involved in a supposed plot to target the Israeli embassy in London.
“Iran in no uncertain terms categorically rejects any involvement in such actions and confirms that we have not been informed of any allegations via proper diplomatic channels.
“Iran has urged the UK to engage so that we may assist any probe into credible allegations. Timing and lack of engagement suggest that something is amiss.”
