UK police have arrested five men, including four Iranian nationals, on suspicion of “terrorism offences”, police have said.

The arrests were carried out in London, Swindon and the Greater Manchester area and were related to “a suspected plot to target a specific premises”, London’s Metropolitan police said in a statement.

The men, aged between 29 and 46, were arrested on suspicion of “preparation of a terrorist act” and remain in custody, the police said.

The nationality of one of the men was still being established, they said.

Counter-terrorism police had been in contact with the site allegedly targeted to make them aware and to provide relevant advice and support but it had not been identified for operational reasons, police said.

“This is a fast-moving investigation and we are working closely with those at the affected site to keep them updated,” Cmdr Dominic Murphy, head of the Met’s counter-terrorism command, said.

“The investigation is still in its early stages, and we are exploring various lines of inquiry to establish any potential motivation as well as to identify whether there may be any further risk to the public linked to this matter.

“We understand the public may be concerned and, as always, I would ask them to remain vigilant and if they see or hear anything that concerns them, then to contact us.”

Murphy added: “We are working closely with local officers in the areas where we have made arrests today and I’d like to thank police colleagues around the country for their ongoing support.”

Officers are carrying out searches at a number of addresses in the Greater Manchester, London and Swindon areas in connection with the investigation.

The arrests and searches are being supported by officers from Greater Manchester police and Wiltshire police, as well as colleagues from counter-terrorism policing from across the country.

Press Association and Agence France-Presse contributed to this report