The UN voiced alarm Monday at reports that several governments used Israeli phone malware to spy on activists, journalists and others, stressing the urgent need for better regulation of surveillance technology.

The reports about the Pegasus spyware "confirm the urgent need to better regulate the sale, transfer and use of surveillance technology and ensure strict oversight and authorisation", UN rights chief Michelle Bachelet said in a statement.

A collaborative investigation by The Washington Post, The Guardian, Le Monde and other media outlets revealed potentially far more extensive spying than previously thought using the malware from Israel's NSO Group, capable of switching on a phone's camera or microphone and harvesting its data.

Bachelet described the revelations as "extremely alarming", saying they "seem to confirm some of the worst fears about the potential misuse of surveillance technology."

She recalled that the UN had repeatedly flagged the dangers of authorities using surveillance tools to hack phones and computers of legitimate journalists, activists and political opponents in the name of public safety.

"Use of surveillance software has been linked to arrest, intimidation and even killings of journalists and human rights defenders," she added, also warning that broad use of such technologies could lead to self-censorship.

The UN High Commissioner for Human Rights said surveillance measures can only be justified "in narrowly defined circumstances, with a legitimate goal" such as "investigations into serious crimes and grave security threats."

"If the recent allegations about the use of Pegasus are even partly true, then that red line has been crossed again and again with total impunity."

Bachelet said companies involved in developing and distributing surveillance technologies should ensure their technologies are not used to violate human rights.

And she said states should halt surveillance that violates human rights and protect individuals from companies abusing their right to privacy, including by regulating spying technology.