The Foreign Office has been targeted by a "highly motivated and well-resourced" group of cyber-hackers which has been linked to Russia.

Hackers targeted civil servants with a "spear-phishing" campaign, in which people were sent targeted emails in an attempt to trick them into downloading malicious files.

F-Secure, a cybersecurity firm, said that the malicious files contained hidden programmes which enabled the hackers to take total control of a victim's computer.

It said that the hackers had an interest in "intelligence gathering related to foreign and security policy" and had also targeted military personnel, officials and journalists in Eastern Europe and the South Caucasus.

Another cybersecurity expert told the BBC the hackers were linked to Russian attempts to influence the outcome of the US election. Two of the addresses used by the hackers were linked to the US attacks.