Facebook agreed in February to pay $19 billion in cash and stock for WhatsApp, which had around 450 million users at the time.
The deal has passed regulatory muster in the U.S., but is still being reviewed by European authorities.
“I think we’re going to have an opportunity for WhatsApp to connect two or three billion people because by working with us they’re just now going to have so many more resources and opportunities,” Zuckerberg said at an appearance in Mexico City.
Facebook at the moment has about 1.3 billion monthly active users and wants to connect everyone in the world.
He said Mexico’s Internet penetration rate of around 50% is above the world average, but that still leaves 60 million people in the country not connected. Facebook is trying to work with Internet service providers, operators and governments to get more people connected, he said.
The event was organized by the Telmex Foundation of billionaire Carlos Slim, whose phone company is the biggest Internet and mobile service provider in Mexico. Telmex had no immediate information on any potential agreement with Facebook.