Two men have been arrested as part of a large scale fraud investigation into money laundering linked to UK extremists travelling to Syria.
Metropolitan Police said the men, aged 23 and 29, were arrested following searches at six addresses across London.
The men were arrested as part of an ongoing fraud investigation where elderly victims are tricked into giving their bank details over the phone by people posing as police officers.
As part of the scam, elderly victims are 'cold called' on their home phone by the impersonator and informed their bank account has been compromised and then deceived into transferring money to an account under the control of the suspect.
Police said one victim lost approximately £150,000 as a result of this fraud.
A Met Police spokesperson added: "Members of the public are strongly advised, if you receive a call like this from someone claiming to be a police officer, hang up the phone, wait at least five minutes to make sure the phone line has cleared, or use another phone line, before ringing the phone number on your bank card."
Police are also reminding people never to give their bank details or pin down the phone or to someone who comes to your front door.