Peter Ricketts’ warning comes as UAE accused of using Pegasus spyware to hack into mobile phone at Downing Street

Boris Johnson should “pay close attention” to basic rules of cybersecurity, a former national security adviser has said, after it emerged that the United Arab Emirates was accused of hacking into a mobile phone at Downing Street.

Peter Ricketts, who held the post between 2010 and 2012, said the cyber-attack demonstrated that “commercially made” Pegasus software from NSO Group allowed a “wide range of actors” to engage in sophisticated espionage.

Anybody with access to secret information needed to be aware of the fast-changing risk, the peer added, including the prime minister, who was forced to change his mobile number last year after it emerged it had been available online.

“It’s vital that anyone with access to sensitive material up to and including the PM have to pay close attention to the basic rules of cybersecurity, including their phone numbers,” Ricketts said.

Johnson was forced to suddenly change his mobile phone last spring after it emerged that his number had been available online for 15 years. It was published on a thinktank press release from 2006 and never deleted.