Facebook Inc said its workforce is 31% female, the fourth major technology company to report its numbers amid a Silicon Valley debate over diversity.

Facebook, whose chief operating officer Sheryl Sandberg has been vocal about the need for women to be represented in leadership roles, said women make up 15% of technical employees and 23% of senior managers.

Also, 91% of employees at the world’s largest social-networking service are white or Asian, the company said in a blog post overnight.

The numbers from the Menlo Park, California-based company are in line with those from Yahoo Inc, Google Inc and LinkedIn Corp, which made similar disclosures in the past month.

The figures highlight a lack of minorities and women at all of the companies, an issue that Sandberg helped bring into the spotlight with her “Lean In” campaign.

“Since our strategic diversity team launched last year, we’re already seeing improved new hire figures and lower attrition rates for underrepresented groups,” Maxine Williams, Facebook’s global head of diversity, said in the post. “As these numbers show, we have more work to do – a lot more.”

The numbers don’t differ much from those of the other Silicon Valley Web companies. Google is 30% female, while Yahoo is 37% and LinkedIn is at 39%.

Facebook is the first to disclose the makeup of its technical workforce, which shows an even bigger gap – 94% white or Asian, with only 3% Hispanic and 1% black.

Facebook said it’s teaming up with several organisations, including the National Center for Women & Information Technology and the National Society of Black Engineers to improve diversity.

Google last week introduced “Made With Code”, an organisation to inspire girls to write software by showing them role models and teaching them introductory coding. The group said it’s committing US$50 million (RM16.1 million) to support programmes that get more women into computer science.