Iranian hackers launched cyber attacks on key parts of British infrastructure, gaining access to MPs' mobile phone numbers, in a major breach just before Christmas, according to reports.
The 23 December attacks are also said to have hit UK private-sector firms including the Post Office and banks, as well as local government networks. Sky News yesterday reported the campaign is still continuing.
The National Cyber Security Centre (NCSC) said: "We are aware of a cyber incident affecting some UK organisations in late 2018.
"The NCSC has worked with victims and advised on mitigation measures."
Among the personal details reportedly stolen were the email address and mobile phone number of Post Office boss Paula Vennells.
Cyber security experts in California said the attack came from the Iranian Revolutionary Guard. At least 10 peers and MPs’ mobile phone numbers were among the data harvested by the hackers, according to the report.
"As we've seen, you can do anything… influence elections, in particular. You can start to impersonate people within that government as well and be utterly convincing," Lewis Henderson, vice-president of threat intelligence at cyber security company Glasswall, told Sky News.
"The levels of trust that the global address list puts in place is completely eroded once you've lost that information, once it's out there in the hands of the attackers.
"We know that they could be impersonating members of our own government and starting to alter and disrupt communications."