By Katie Paul

(Reuters) -Facebook-owner Meta Platforms Inc has cut plans to hire engineers by at least 30% this year, CEO Mark Zuckerberg told employees on Thursday, as he warned them to brace for a deep economic downturn.

"If I had to bet, I'd say that this might be one of the worst downturns that we've seen in recent history," Zuckerberg told workers in a weekly employee Q&A session, audio of which was heard by Reuters.

Meta has reduced its target for hiring engineers in 2022 to around 6,000-7,000, down from an initial plan to hire about 10,000 new engineers, Zuckerberg said.

Meta confirmed hiring pauses in broad terms last month, but exact figures have not previously been reported.

In addition to reducing hiring, he said, the company was leaving certain positions unfilled in response to attrition and "turning up the heat" on performance management to weed out staffers unable to meet more aggressive goals.

"Realistically, there are probably a bunch of people at the company who shouldn't be here," Zuckerberg said.

"Part of my hope by raising expectations and having more aggressive goals, and just kind of turning up the heat a little bit, is that I think some of you might decide that this place isn't for you, and that self-selection is OK with me," he said.

The social media and technology company is bracing for a leaner second half of the year, as it copes with macroeconomic pressures and data privacy hits to its ads business, according to an internal memo seen by Reuters on Thursday.

The company must "prioritize more ruthlessly" and "operate leaner, meaner, better executing teams," Chief Product Officer Chris Cox wrote in the memo, which appeared on the company's internal discussion forum Workplace before the Q&A.

"I have to underscore that we are in serious times here and the headwinds are fierce. We need to execute flawlessly in an environment of slower growth, where teams should not expect vast influxes of new engineers and budgets," Cox wrote.

The memo was "intended to build on what we've already said publicly in earnings about the challenges we face and the opportunities we have, where we're putting more of our energy toward addressing," a Meta spokesperson said in a statement.

The guidance is the latest rough forecast to come from Meta executives, who already moved to trim costs across much of the company this year in the face of slowing ad sales and user growth.

Tech companies across the board have scaled back their ambitions in anticipation of a possible U.S. recession, although the slide in stock price at Meta has been more severe than at competitors Apple and Google.