Facebook founder and chief executive Mark Zuckerberg on Thursday joined the list of billionaires who have pledged to give the most of their wealth to charity.

According to business magazine Forbes, Zuckerberg's fortune is worth $6.9bn.

The 26-year-old chief executive of the social networking site announced his intention by signing up for Giving Pledge, an initiative set up by Microsoft co-founder Bill Gates which urges signatories to donate to charity.

Zuckerberg is among the 17 billionaires who recently signed up to the pledge. About 57 of the world's wealthiest people have also pledged to give at least 50 per cent of their wealth to the needy.

"People wait until late in their career to give back. But why wait when there is so much to be done?" asked Zuckerberg.

"With a generation of younger folks who have thrived on the success of their companies, there is a big opportunity for many of us to give back earlier in our lifetime and see the impact of our philanthropic efforts," he added.

The donation is considered a moral commitment, a symbolic gesture and is not a legally-binding contract, the Guardian report added on Thursday.