Millions of computers using Intel chips are prone to hacking because of a flaw that went unnoticed for a decade, it has emerged.

Software giants are currently working on a fix for the flaw but industry experts have warned it could potentially slow down all devices running the chips by up to 30 per cent.

The flaw could allow hackers a "persistent and undetectable backdoor into someone's computer", Mike Godfrey, cyber expert at Insinia Security told the Telegraph.

The flaw grants access to a computer's kernel, which runs and stores every function on the device, and means an outsider could potentially bypass antivirus or firewall security software without the owner knowing. It could allow malicious software to steal passwords and sensitive files or cryptographic keys, necessary for keeping us safe online.

The National Cyber Security Centre, an arm of GCHQ issued a statement on Wednesday afternoon advising individuals to install updates when they became available.