Police investigating a large-scale fraud linked to extremists travelling to Syria have made seven arrests.

Officers from the Metropolitan Police's counter-terrorism command raided six addresses in London and one address in Luton, Scotland Yard said in a statement.

Six men aged between 21 and 38 were arrested on suspicion of conspiracy to commit fraud and money laundering, and one woman, aged 32, for money laundering.

It is alleged that "unsuspecting, vulnerable" elderly people were cold called by someone pretending to be a police officer.

A 46-year-old woman was also arrested at one of the addresses on suspicion of a separate child abduction offence, and has been bailed.

The arrest is in relation the investigation of a girl who travelled to Turkey, and whose current whereabouts are unknown.