A pedestrian walks in front of Meta logo in front of Facebook headquarters in Menlo Park, California, on October 28, 2021 (AFP)

Meta's Facebook and Instagram hired back "dozens" of the 21,000 employees that were fired a few months ago during a wide campaign to cut costs following forecasts of slowing profit this year and anticipated recession, Business Insider reported on Friday.

The tech giant went into a hiring spree during the Covid-19 pandemic as online shopping surged during the lockdown, which generated billions for the firm from ads, its primary source of revenue.

Mark Zuckerberg announced 2023 to be the “year of efficiency" and that the firm halted hiring.

"This will be tough and there's no way around that. It will mean saying goodbye to talented and passionate colleagues who have been part of our success," Meta chief said then in a mass internal email.

But the report mentioned that Meta has “quietly picked up hiring in certain areas” - mainly engineers and technical personnel - as earnings began to rise again.

Meta's revenue has soared 145% since January, landing nearly a $306 per share value as of recently after beating Wall Street forecasts.

Hundreds of open roles were spotted on the company's website across the United States, the report added, noting that individuals will have to re-apply for the positions through an “alumni portal".

Zuckerberg said during the earnings calls on July 26 that he will be “continuing to run the company as lean as possible” and that headcount growth would be “relatively low", which was considered by observers as a hint of plans to reinstate hiring.

“That said, as part of this year’s layoffs, many teams chose to let people go in order to hire different people with different skills that they need, so much of that hiring is going to spill into 2024,” he said then.

The company's new social media platform Threads, which was released as a rival to Elon Musk's Twitter, has also contributed to the rise of share value as investors saw the company adding new sources of ad income.

Between the end of 2022 and the beginning of 2023, the tech sector saw the layoff of tens of thousands of employees in a bid to slash costs. Google, Amazon, Spotify, Twitter (now X) after Musk's takeover, Coinbase, and Sophos were among the firms to carry out mass firings.