US Attorney General William Barr testifies before the Senate Judiciary Committee on “The Justice Department’s Investigation of Russian Interference with the 2016 Presidential Election” on Capitol Hill in Washington, DC, on May 1, 2019.Mandel Ngan | AFP | Getty ImagesAttorney General William Barr will ask Facebook CEO Mark Zuckerberg to hold off on his plans to encrypt the company’s three messaging services until officials can determine it will not reduce public safety, BuzzFeed News reported Thursday.Barr’s request is backed by officials in the U.K. and Australia, according to BuzzFeed, which obtained a draft of the open letter, which is dated Oct. 4, ahead of its publication. The letter builds on concerns about Facebook’s plans to integrate and encrypt its messaging services across Messenger, Instagram and WhatsApp. A New York Times investigation published Saturday found that encrypted technology helps predators share child pornography online in a way that makes it much harder for law enforcement to track down.”Security enhancements to the virtual world should not make us more vulnerable in the physical world,” the draft letter viewed by BuzzFeed said. “Companies should not deliberately design their systems to preclude any form of access to content, even for preventing or investigating the most serious crimes.”In the letter, Barr and U.K. Home Secretary Priti Patel, U.S. Secretary of Homeland Security Kevin McAleenan, and Australian Minister for Home Affairs Peter Dutton ask Facebook to create a way for law enforcement to access illegal content, according to BuzzFeed.”Risks to public safety from Facebook’s proposals are exacerbated in the context of a single platform that would combine inaccessible messaging services with open profiles, providing unique routes for prospective offenders to identify and groom our children,” the letter said.In a statement, a Facebook spokesperson said, “We believe people have the right to have a private conversation online, wherever they are in the world.” Facebook said it has been consulting with experts in child safety as well as governments and other tech companies to ensure its newly encrypted services are secure. Facebook “strongly oppose[s] government attempts to build backdoors because they would undermine the privacy and security of people everywhere,” according to the statement.Facebook is not the first tech company to butt heads with the government over encryption. Just a few years ago, Apple was in a standoff with the Federal Bureau of Investigation over access to the iPhone of a shooter in the 2015 San Bernardino attack. A federal judge asked Apple to help the FBI unlock the phone, but Apple CEO Tim Cook called the order “dangerous” because it could allow the government to overstep in future cases and demand technology companies to surveil users. The Department of Justice ultimately said it was able to access the phone’s data without Apple and asked the judge to drop the case.Facebook’s plans to integrate its three platforms also has raised antitrust concerns as investigations into Facebook’s competitive practices will likely scrutinize its past acquisitions of Instagram and WhatsApp. While the letter does not seem to touch on these concerns based on BuzzFeed’s report, postponing the integration would buy investigators more time to understand the antitrust implications of those acquisitions before Facebook scrambles the eggs, preempting a potential breakup.The Department of Justice did not immediately respond to requests for comment.Subscribe to CNBC on YouTube.