The former chief operating officer of Meta, Sheryl Sandberg, is leaving the company's board of directors.

Ms Sandberg, one of the most high-profile women in the tech industry, said that "this feels like the right time to step away" as Meta is "well-positioned for the future".

She will serve as an informal advisor to the company going forward.

Meta CEO Mark Zuckerberg thanked her for the "extraordinary contributions" to the company.

Ms Sandberg, 54, joined the firm when it was a small start-up named Facebook. A veteran of Google, she helped turn its advertising business into a profit powerhouse, as the company grew to include Instagram, WhatsApp and Messenger.

Her books, including Lean In: Women, Work, and the Will to Lead - which she described as a "sort of feminist manifesto" - made her a global celebrity.

The company also faced massive criticism under her watch, including misinformation during the 2016 election, the Cambridge Analytica privacy scandal in 2018, and the Capitol riot in 2021.

She posted about her departure in a Facebook post on Wednesday, saying she has a "heart filled with gratitude and a mind filled with memories".

She said that serving as Facebook and Meta's COO for over 14 years and a board member for 12 years was "the opportunity of a lifetime".

Shortly after Ms Sandberg's announcement, Mr Zuckerberg responded with a short reply.

"Thank you Sheryl for the extraordinary contributions you have made to our company and community over the years," he commented on her post. "Your dedication and guidance have been instrumental in driving our success and I am grateful for your unwavering commitment to me and Meta over the years."

Meta is facing new challenges as countries tighten social media regulations and iPhone maker Apple changes its privacy rules, hitting the social media firm's targeted ad business.

Growth in the number of Facebook users in key markets, such as the US, has been stalled, and it has lost younger users to rivals such as TikTok.