"I believe the future of communication will increasingly shift to private, encrypted services where people can be confident what they say to each other stays secure and their messages and content won't stick around forever," Zuckerberg wrote on his Facebook page.

"This is the future I hope we will help bring about."

The announcement suggests a new emphasis for Facebook as it seeks to navigate a crisis over privacy and data protection amid revelations on how it handles personal user data.

Zuckerberg said he sees a major shift for Facebook which over 15 years has helped build what he called "the digital equivalent of a town square."

He said that in the current environment, "people increasingly also want to connect privately in the digital equivalent of the living room."

Facebook has built the world's largest online platform with some 2.3 billion active users but has been criticized for enabling misinformation and manipulation, and for gathering vast amounts of personal data which may be used for targeted advertising.

A series of revelations on Facebook's handling of personal data has forced the company to review all its operations, and Zuckerberg has been pledging to improve data protection.

His latest missive suggests however that a more broadly-focused Facebook will move away from being a public platform to emphasize smaller-scale conversations that are secure and encrypted.

"Today we already see that private messaging, ephemeral stories, and small groups are by far the fastest growing areas of online communication," he said.

"Many people prefer the intimacy of communicating one-on-one or with just a few friends. People are more cautious of having a permanent record of what they've shared. And we all expect to be able to do things like payments privately and securely."

He said public social networks would "continue to be very important in people's lives" but that with growing demand for private interactions "there's also an opportunity to build a simpler platform that's focused on privacy first."