The police have asked retailers to blow the whistle on suspected terrorists.
Life Savers, a high-profile campaign, was launched on Monday by the Metropolitan Police and retailers are urged to call a confidential hotline if they suspect anyone of criminal activity.
Terrorist groups - including Osama bin Laden's al-Qaeda network - are known to operate in the UK, using various types of fraud to procure cash to fund their activities.
Peter Clarke, head of the Met's anti-terrorist branch, said London and the UK as a whole is on the radar of a number of terrorist groups.
Retailers are urged to brief staff about the threat and to encourage them to use the hotline to report customers who arouse suspicion.
'Terrorists need money and often commit cheque and credit card fraud to finance their activities,' said Clarke.
'Among the methods used is the creation of identities to set up bogus bank accounts. Suspects then use cheque-books to purchase goods that are later returned for cash refunds.'
He added: 'Credit cards are also cloned and used to buy goods which are later sold.'
- Police have launched a nationwide operation to build profiles of individuals who provide financial support to terrorists by committing credit card fraud.
The Life Savers hotline number is 0800 789321.