Suspected Russian hackers spied on US federal agencies

FBI to investigate after US Treasury and Department of Commerce believed to have been targeted

Russian hackers are being accused of carrying out the biggest cyber-raid against the US for more than five years, targeting federal government networks in a sophisticated attack, according to American officials and sources.

The hackers, linked to Russian spy agencies, were able to monitor internal emails at the US Treasury and Department of Commerce and may have compromised other bodies, in what is being described as a highly sophisticated state-level attack.