Police have been given more time to question four Iranian men over an alleged terror plot in the UK.

The men were arrested on 3 May on suspicion of preparation of a terrorist act, the Metropolitan Police said.

The suspects, detained under the Terrorism Act, can be held until 17 May after the force obtained warrants to further extend their detention.

A fifth Iranian man, who was detained under the Police and Criminal Evidence Act, has been released on bail with conditions.

The five men – two aged 29, a 40-year-old, a 24-year-old and another aged 46 – on 3 May – were arrested in Swindon, west London, Stockport, Rochdale and Manchester.

The Met said officers were continuing search a number of addresses in the Greater Manchester, London and Swindon areas.

Cdr Dominic Murphy, head of the Met’s counter terrorism command, said it was a “significant and highly complex investigation”.

He urged the public not to “speculate or share information” that has not been confirmed by police.

The Met has previously said it believes “a specific premises” was the target of the suspected plot.

The BBC understands the alleged target was the Israeli embassy in London, as first reported by the Times. Police have not yet confirmed the embassy was the suspected target, citing operational reasons.

Three other Iranian men – aged 39, 44 and 55 – were arrested on the same day in London in relation to a separate counter-terrorism investigation.

They were arrested under section 27 of the National Security Act, which covers offences deemed a threat to national security.

On Friday, police said a fourth man, 31, had been arrested in north-west London as part of the same investigation.

Cdr Murphy has said police are not linking the two investigations.

Speaking in the Commons on Tuesday, Home Office minister Dan Jarvis described the two separate investigations as “some of the largest counter-state threats and counter-terrorism actions that we have seen in recent times”.