A US civil servant who browsed porn sites at work ended up infecting an entire government network with malware, an official report found.

The US Geological Survey employee visited at least 9,000 porn web pages, an internal investigation found, an unwittingly downloaded malware which then “exploited the USGS network”.

Investigators also found that the employee’s Android phone was infested with malware from porn sites, and said that the employee had also saved porn he watched on his work PC onto a USB device.

The malware in question is associated with ransomware attacks, in which a malicious agent uses computer code to take over a person’s computer and demands money in exchange.

Auditors at the US Department of the Interior ripped into the US Geologicial Survey for its lack of IT preparedness, saying the employee’s workplace – an EROS centre in South Dakota - had not locked down access to rogue websites and had no restrictions on the use of unauthorised USBs.