A vigilant employee prevented a £1.5m fraud against Lincolnshire County Council when scammers tried to falsely change a contractor's bank account details.

The council's IT security blocks most spam and malicious emails, but a more sophisticated email scam had reached finance staff informing them a supplier had changed their bank account information.

Lucy Pledge, audit and risk manager at the council, said: "The correspondence to the council looked entirely genuine and identical to official letters from this supplier.

"Because the staff member took the time to double-check using an independent phone number - not the one in the letter - they quickly discovered this was fraudulent.

"The next payment due to be made to this supplier was £1.5m."

The council's IT systems blocked 7993 malicious emails during May alone, on top of 276,241 emails deemed to be spam.

Cllr Alex Maughan, the council's fraud champion, said: "Bank mandate fraud is just one type of scam that the council is targeted with every day.

"We take all fraud seriously and our staff receive specific training to pick up on anything that may not be genuine.

"We are not an easy target and continue to make every effort to protect public money."

The incident was reported to Action Fraud.