Zuckerberg noted the milestone anew at Meta's annual gathering of shareholders and as the social media behemoth vies with Google, Microsoft, OpenAI and others to be a leader in Gen AI.

It was not clear how much Meta AI use involved people seeking out the chatbot versus passive users of Meta AI, as it is built into features in its family of apps.

Since Google debuted AI Overviews in search results a year ago, it has grown to more than 1.5 billion users, according to Google chief executive Sundar Pichai.

"That means Google Search is bringing Gen AI to more people than any other product in the world," Pichai said.

Google's AI Overviews are automatically provided summaries of search results that appear instead of the previous practice of simply showing pages of blue links to revelant websites.

Pichai said last week that Google's dedicated Gemini AI app has more than 400 million monthly users.

Tech rivals are rapidly releasing new AI products despite ongoing challenges with preventing misinformation and establishing clear business models, and little sense of how the tech will affect society.

Meta unveiled its first standalone AI assistant app on April 29, giving users a direct path to its Gen AI models.

"A billion people are using Meta AI across our apps now, so we made a new standalone Meta AI app for you to check out," Meta CEO and founder Mark Zuckerberg said in a video posted on Instagram at the time.

Zuckerberg said the app "is designed to be your personal AI" and would be primarily accessed through voice conversations with the interactions personalized to the individual user.

Use of Meta AI is growing fastest on WhatsApp, according to chief financial officer Susan Li.

"Our focus for this year is deepening the experience and making Meta AI the leading personal AI," Zuckerberg said when Meta announced quarterly earnings at the end of April.