By Gordon Corera
Security correspondent, BBC News
An MP has told the BBC his emails person been stolen and helium fears they volition beryllium made public.
The SNP's Stewart McDonald said the hack took spot successful January and helium wanted to pre-empt immoderate work sharing them.
The radical liable are believed to beryllium linked to Russia's spy services.
The UK's cyber-defence bureau has warned astir targeted attacks connected politicians successful caller weeks.
On 13 January Mr McDonald was walking down the thoroughfare erstwhile helium received a notification connected his phone.
There was a caller connection successful the MP's backstage email account.
He glanced astatine it - it was from a subordinate of his staff.
There was thing suspicious astir it and it came from the unit member's existent email account.
The connection said determination was a password protected papers attached which had a subject update connected Ukraine.
This made consciousness arsenic the MP for Glasgow South had taken a adjacent involvement successful Ukraine for a fig of years, receiving the bid of merit from the Ukrainian government.
He had besides been the defence spokesperson for the SNP until past year.
Mr McDonald clicked connected the document.
It brought up a login leafage for the email relationship helium was using. He enactment successful his password.
Strangely, it past brought up a blank page.
Perhaps it was not loading decently connected his phone, helium thought?
He would inquire the unit subordinate to resend it adjacent clip they spoke.
What helium did not cognize yet was that a hacking radical believed to beryllium linked to Russia's quality services was present wrong his relationship - a radical which has connected different occasions published emails belonging to nationalist figures.
A fewer days later, the subordinate of unit mentioned to the MP that helium had been locked retired of his idiosyncratic email relationship due to the fact that of suspicious enactment and was having problems trying to beryllium his individuality and get backmost in.
"I meant to inquire you astir that email you sent. I couldn't unfastened the attachment," Mr McDonald recalls saying to him.
"I didn't nonstop immoderate email," the subordinate of unit replied.
Alarm bells were present ringing for the MP.
The proposal was to interaction the National Cyber Security Centre (NCSC), an limb of the UK's quality agency, GCHQ.
Working with the parliamentary information team, they asked for the email and attachment to beryllium sent truthful they could analyse it.
The NCSC was already preparing to contented an advisory astir a hacking group, known arsenic Seaborgium saying it was liable for a highly targeted run against individuals including politicians, activists and journalists.
That advisory tallies intimately with what Mr McDonald experienced - the compromise of individuals, similar his unit member, truthful they tin successful crook beryllium utilized to nonstop emails to the superior target.
These are highly targeted and blase attacks against a tiny fig of radical alternatively than the broad-bush sending of malicious emails that are usually seen.
Sources accidental the advisory was long-planned and corroborate the aforesaid radical is believed to beryllium down the hack of Mr McDonald's account.
The British authorities has not formally accused the Russian authorities of being down the radical oregon the hacks but wrong the wider cyber-security assemblage the radical has been identified arsenic linked to Russia's quality services.
The aforesaid radical is said to person published hacked emails and documents by different individuals, including the erstwhile caput of MI6 Sir Richard Dearlove, arsenic good arsenic writer Paul Mason.
Mr McDonald says helium has decided to spell nationalist to pass others of the risks and bounds the imaginable harm arsenic helium waits to spot what the hackers bash with the stolen material.
"If it is so a malicious state-backed group, then, successful enactment with what I've seen elsewhere, I expect them to dump immoderate of the accusation online.
"And I tin expect them to manipulate and fake immoderate of that contented and I privation to get retired up of that to guarantee immoderate disinformation onslaught against maine is discredited earlier it's adjacent published," helium told the BBC.
"An incidental has been reported to america and we are providing the idiosyncratic with support," a spokesperson for the NCSC told the BBC.
"The NCSC regularly provides information briefings and guidance to parliamentarians to assistance them support against the latest cyber threats. This includes adept proposal for MPs and their unit disposable connected the NCSC website."
Mr McDonald continues to beryllium unsure what - if thing - volition beryllium done with the stolen material. Even though helium was alert of the risks earlier the incidental helium has since past taken further steps to unafraid his accounts.
"It tin drawback radical adjacent those who are live to these threats," helium said.