The incident began nearly three weeks ago, on the evening of 20 December. It has disrupted the media group’s internal technology infrastructure and some of its behind-the-scenes services.
At the time it said: “We believe this to be a ransomware attack but are continuing to consider all possibilities.”
Although Guardian Media Group’s online publishing operation has been “largely unaffected”, production of the physical newspaper has been impacted.
In an update in Saturday’s edition, editor-in-chief Katharine Viner wrote: “Before Christmas, we were hit by serious disruption to our network and IT systems. It has affected us in many different ways, one of which is that some of our newspaper design and layout systems have been challenged.
“This has made producing the newspaper more difficult.”
Viner said the group’s teams were striving to get things back to normal, but some content had suffered. “It has meant that we have occasionally been unable to bring you some stories you would expect to find, including very late breaking news and sport”.
Some content is also appearing in a different location within the paper, which was the case with Saturday’s puzzles.
“We have already received many supportive messages from readers – thank you. We appreciate your support all year round and we ask for your continued patience,” Viner concluded.