Dozens of Thai democracy activists were targeted by the controversial Israeli spyware known as Pegasus during the height of intense anti-government protests, according to an international digital rights group report.

Massive demonstrations engulfed Thailand's capital Bangkok two years ago as thousands called for greater civil freedoms, as well as a loosening of the strict lese-majeste laws that prevent any criticism of the monarchy.

The report by Canadian cybersecurity watchdog Citizen Lab in partnership with Thai groups iLaw and DigitalReach, identified some 30 activists, academics, lawyers and NGO workers -- mostly connected to civil rights organisations -- whose mobile devices were affected.

"The infections occurred from October 2020 to November 2021, coinciding with a period of widespread pro-democracy protests, and predominantly targeted key figures in the pro-democracy movement," the report stated.

Pegasus software, created by Israeli firm NSO Group, can extract data and activate cameras or microphones once it has successfully infiltrated a mobile device.

The report stops short of saying definitively who was behind the use of the spyware, though it notes that NSO Group says they only sell the technology to governments.

In its own executive summary of the findings the Thai NGO iLaw said: "It can be circumstantially concluded that the use of Pegasus against dissidents would be of significant benefit to the Thai government."

Among those targeted by Pegasus was activist and monarchy critic Panusaya Sithijirawattanakul
Among those targeted by Pegasus was activist and monarchy critic Panusaya Sithijirawattanakul AFP / Jack TAYLOR

Among those targeted, Citizen Lab said, were the lese majeste lawyer Arnon Nampa, protest leader Panusaya Sithijirawattanakul and activist Jatupat Boonpattararaksa.

Panusaya is currently on bail and facing 10 royal defamation charges, while Jatupat was denied bail earlier this year after also being charged with insulting the monarchy.

Those affected were tipped off in November 2021 when Apple sent out a notification informing them their devices had been targeted by state-backed attacks.

Amnesty International, following an independent investigation, condemned the hacking.

"These new revelations are a shocking example of just how low authorities might stoop to control peaceful dissent," said technologist Etienne Maynier.

"It is worth remembering that this is only what has been found so far, and the scale of surveillance attempts could be bigger and more damaging."

It is the latest such case of the Israeli software being used to surveil dissidents.

The NSO Group is currently being sued in the US by Apple, which alleges the firm's spyware was used to infiltrate a number of iPhones worldwide.