Banks have been warned that it's "not fair" to automatically blame customers for money lost through a scam.
Customers transferred nearly £240m to fraudsters last year, only a quarter of which was refunded by financial firms.
The Financial Ombudsman service said fraudsters' growing sophistication meant it was wrong to assume losses were due to customer carelessness. The service, which resolves customer disputes, said victims who lost money had a good chance of being reimbursed.
"It's not fair to automatically call a customer grossly negligent simply because they've fallen for a scam.
"That's especially true in light of the sophisticated way criminals exploit banks' security systems - and convince customers that their money is at risk," Financial Ombudsman Service chief ombudsman and chief executive Caroline Wayman said.
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