A Russia-linked hacking gang has claimed credit for the cyberattack that has crippled Royal Mail and is threatening to publish stolen data from the company online.
The LockBit ransomware gang published an update on its official forum, warning it would publish "all available data" on 9 February.
The Telegraph revealed in January that the LockBit gang, which is believed to have close links to Russia, was behind the attack.
Royal Mail’s international export services were shut down after the attack, causing significant delays to overseas mail and leaving millions of parcels stuck in limbo.
Hackers are understood to have shut down machines including those used to print custom labels.
Royal Mail said It has since developed ad-hoc alternative systems to get mail moving, but this remains subject to delays.
A day after the hack, the LockBit gang printed out ransom notes demanding payment in order to unlock the machines.
The note sent to Royal Mail Source: Daniel Card
The LockBit gang largely communicates in Russian on hacking forums and has previously stated it benefits from the "hostile attitude of the West towards Russia," which allows it to "operate freely within the borders of the former Soviet countries".
Simon Thompson, Royal Mail's chief executive, previously said it was believed that no customer data had been stolen as part of the attack.
In its latest status update following the hack, Royal Mail said: "We continue to make progress in exporting an increasing number of items to a growing number of international destinations.
A Royal Mail spokesman said: “Royal Mail is aware that an unauthorised third-party has said it plans to publish some data allegedly obtained from our network.
“At this stage of the investigation, we believe that the vast majority of this data is made up of technical program files and administrative business data.”