The WhatsApp messaging service is suing an Israeli surveillance firm, accusing it of helping government spies break into the phones of security targets.

In a lawsuit filed in federal court in San Francisco, WhatsApp, which is owned by Facebook, accused the group NSO of facilitating government hacking sprees in 20 countries.

NSO has denied the allegations.

“The sole purpose of NSO is to provide technology to licensed government intelligence and law enforcement agencies to help them fight terrorism and serious crime,” the company said in a statement.

WhatsApp said the attack exploited its video calling system in order to send malware to the mobile devices of users. The malware would then allow governments and intelligence organisations to secretly spy on a phone’s owner.

NSO’s phone hacking software has already been implicated in a series of human rights abuses across Latin America and the Middle East.

The company came under particular scrutiny over the allegation that its spyware played a role in the death of Washington Post journalist Jamal Khashoggi, at the Saudi Consulate in Istanbul a little over a year ago.

-AAP