UK officials from 10 Downing Street and the Foreign and Commonwealth Office were reportedly hacked by the government of the United Arab Emirates (UAE) using the Israeli-made Pegasus software.
According to the New Yorker, Israeli spyware was used to infect a device connected to the No. 10 network, including British Prime Minister Boris Johnson's mobile on 7 July 2020.
The National Cyber Security Centre tested Johnson's mobile and several other phones used by Downing Street officials but was unable to locate the infected devices, the magazine reported.
The Foreign Office did not deny the reports. A spokesperson said: "We do not routinely comment on security matters."
The infamous Israeli-made Pegasus spyware was also suspected of having infected the Foreign Office on at least five occasions between July 2020 and July 2021, according to researchers. This was linked to operators in the UAE, India, Cyprus and Jordan.
READ: Israel rejects Ukraine's request for Pegasus spyware over fears of angering Russia
"When we found the No.10 case, my jaw dropped," said John Scott-Railton, a senior researcher at the University of Toronto's internet watchdog, Citizen Lab, which has been tracking the use of Pegasus.
He alleged the UK Government was "spectacularly burned" after "underestimating the threat from Pegasus."
Bill Marczak, a researcher at Citizen Lab, said Pegasus was likely installed on phones in both Number 10 and the Foreign Office for the "exfiltration of data".
In response, a spokesperson for NSO Group said: "The information raised regarding these allegations are, yet again, false and could not be related to NSO products for technological and contractual reasons."
"NSO continues to be targeted by a number of politically motivated advocacy organisations, like Citizens Labs and Amnesty, to produce inaccurate and unsubstantiated reports based on vague and incomplete information."
"We have repeatedly co-operated with governmental investigations, where credible allegations merit."
NSO software was made infamous in July when Citizen Lab exposed numerous governments' misuse of the software through the targetting of around 50,000 phones and devices belonging to journalists, human rights activists and political critics worldwide.
Amongst those client governments were Gulf Arab states, including the UAE, Saudi Arabia and Bahrain.
Apple later filed a lawsuit against NSO and its parent company, OSY Technologies, in an effort to stop the spyware company from targeting any Apple devices.
NSO is an Israeli company specialising in the development of cyber-espionage tools. It was founded in 2010. Following accusations of the extensive use of the software by despotic regimes, the US sanctioning NSO by putting it on a trade blacklist in November last year.