The personal phone of former British Prime Minister Liz Truss from her time as foreign secretary was hacked by agents suspected of working for Russian President Vladimir Putin, the Daily Mail reported on Saturday, Reuters and Agerpres reported.

According to an article in the British press, these agents had access to “top secret details” of negotiations with international allies, in addition to private messages Truss exchanged with his close friend Kwasi Kwarteng, who later became finance minister.

The messages are believed to contain discussions with key foreign ministers of the war in Ukraine, including details of arms shipments. The messages were downloaded for almost a year, writes the Daily Mail with reference to anonymous sources.

A UK government official declined to comment on personal security measures.

The act of hacking was discovered during the Conservative Party leadership campaign during which Liz Truss became prime minister, the Daily Mail reports.

Truss was forced to step down as prime minister last week and was succeeded by Rishi Sunak.

According to an article published in the Daily Mail, among the hacked messages are criticism of Prime Minister Boris Johnson by Truss and Kwarteng, “there is a potential risk of blackmail”.