UK Finance reported 33,115 cases up from 14,947 in the same period last year.

Victims lost a staggering £129.4m between January and June to this type of fraud compared with £57.9m a year earlier.

Impersonation scams are when a criminal pretends to be from a trusted organisation such as a bank or government department and tricks their victim into transferring money using a range of cover stories. These include claiming they need to protect an account from fraud, that a fine or tax needs to be paid or an erroneous refund must be returned.

The rise in cases comes as research by UK Finance shows nearly one in five (19 per cent) people feel uncomfortable saying ‘no’ to a request for personal information from a stranger via email or text, rising to almost a quarter (23 per cent) when it comes to phone calls.

Worryingly, 92 per cent of people admit to saying ‘yes’ because they don’t want to appear rude.

The research found that people use a range of phrases to avoid saying ‘no’, including ‘I’m not sure’, ‘I don’t think so’, ‘Let me think about it’, and ‘I can’t at the moment’. This can give criminals a way in, UK Finance said.

To help people stay safe, the Take Five to Stop Fraud campaign led by UK Finance advises people to:

• STOP: Take a moment to stop and think before parting with your money or information could keep you safe.
• CHALLENGE: Could it be fake? It’s ok to reject, refuse or ignore any requests. Only criminals will try to rush or panic you.
• PROTECT: Contact your bank immediately if you think you’ve fallen for a scam and report it to Action Fraud.

Tony Blake, Take Five fraud expert, said: “Criminals are experts at pretending to be someone they are not – and can fool even the savviest of people, who don’t want to seem rude.

“If someone contacts you unprompted and asks for personal or financial information, stop and take a moment to think – even if they claim to be from an organisation you trust. Only criminals will put pressure on you to act quickly. Remember it’s ok to say no and contact the organisation through a route you know to be genuine.

“The banking and finance industry works to tackle fraud on every front, through investing millions in advanced technology and working closely with the government and law enforcement to stop the criminal gangs responsible.”