Residents are being warned of a scam involving criminals pretending to be from BT.

Fraudsters are claiming to call from BT’s technical department and asking them to enter numbers into their computers.

This enabled the tricksters to access the computers remotely and either install malware which enables them to steal personal data or ransomware, which encrypts the data and asks for money to unlock it.

A spokesman for Essex Police said: “Anyone who receives such calls is advised to hang up and call BT customer services on a mobile phone rather than the landline to establish if they are legitimately trying to contact them.

“They are also asked to report the incident direct to Action Fraud, the UK’s national fraud-reporting centre run by the National Fraud Authority.

“You can either report fraud using its online system, which is available 24 hours a day at http://www.actionfraud.police.uk/, or you can speak to an advisor by calling the reporting line on 0300 123 2040.”