FRAUD investigators at Gloucestershire Police are conducting an inquiry into a telephone scam, in which computer hackers have gained access to people's bank accounts and stolen thousands.
Eleven incidents were reported to police in the last twelve months and in the majority of cases call recipients recognised a potential fraud and hung up.
However three more recent incidences resulted in thousands of pounds being stolen from unsuspecting victims.
The scam involves fraudsters cold-calling people claiming to be working for Microsoft and stating that there is a serious problem with their computer, which they offer to fix for a fee.
Victims have either made a large online payment over the phone, or allowed the caller to remotely connect to their machine while logging onto their bank account.
Detective sergeant Alex Mercurio, from the Force Intelligence Bureau, said this type of fraud was widespread across the UK.
"In order to assist us with enquiries, it is important that anyone who has experienced such an incident should report it to the police, whether they became victims of financial loss or not," he said.
"Valuable information such as a displayed phone number, names of callers and bank account details of suspects could assist in trying to trace and bring offenders to justice."
He added that it was not just the elderly and vulnerable who were falling for the scam.
Harm reduction advisor Kim Mowday, said: "We would advise people never to give out details of their account or pin numbers, unless purchasing something from a certified source.
"Be suspicious of unsolicited calls like this. Microsoft never contact customers in this way or asks for money to fix a problem."
Anyone who has paid for bogus computer support should contact Action Fraud via www.actionfraud.police.uk or call 0300 123 2040.