The hackers were able to look through emails, internal documents and other information related to day-to-day operations of the foreign ministry thanks to a virus "probably accidentally" downloaded by a civil servant, sources were quoted as saying in the report published on Friday.
"It was very embarrassing and caused great stir in government because they didn't know whether they should admit it or not," a source in the Government Communications Headquarters (GCHQ) told the newspaper.
None of the information obtained by hackers was classified, however, it may have damaged relations with allied nations and put some diplomats in danger, the newspaper cited unnamed experts as saying.
The United Kingdom's government did not want to get criticized for the vulnerability of their communication system and decided to hide this incident from the public eye to avoid the "embarrassment," sources were quoted as saying.
In February 2022, the UK government revealed the Foreign Office had been the target of a "serious cyber security incident" due to publishing tender document on its website by mistake. In October of the same year, the UK government admitted that "hostile actors" gained access to personal data of tens of millions of voters.