Sources familiar with WhatsApp's internal investigation into the breach said a "significant" portion of the known victims are high-profile government and military officials spread across at least 20 countries on five continents. Many of the nations are U.S. allies, they said.

The hacking of a wider group of top government officials' smartphones than previously reported suggests the WhatsApp cyber intrusion could have broad political and diplomatic consequences.

WhatsApp filed a lawsuit on Tuesday against Israeli hacking tool developer NSO Group. The Facebook-owned software giant alleges that NSO Group built and sold a hacking platform that exploited a flaw in WhatsApp-owned servers to help clients hack into the cellphones of at least 1,400 users between April 29, 2019, and May 10, 2019.