Facebook CEO Mark Zuckerberg revealed an interesting take on his hiring practises recently.

Speaking at the Mobile World Congress in Barcelona earlier this week, the world's richest technopreneur said: "I will only hire someone to work directly for me if I would work for that person."

He added: "It's a pretty good test and I think this rule has served me well."

The Telegraph reported that the 30-year-old billionaire gave the example of Facebook's chief operating officer, Sheryl Sandberg, who he considers a mentor and "someone who has been instrumental in building Facebook into a business and a healthy organisation."

According to Sky News, there are fewer positions available at Facebook compared to other Silicon Valley firms.

With a company headcount of fewer than 10,000 (Google has 55,000 employees), Zuckerberg said: "The most important thing is to keep your team as small as possible (because) big companies get bloated."

Although the social media giant serves over a billion users in the world, Zuckerberg is adamant on hiring only employees whose values align with the company's.

"Facebook is not a company for everyone in the world," Zuckerberg added.