Facebook lures Africa with free internet - but what is the hidden cost?

Some see Mark Zuckerberg's plan to wire up the continent as a philanthropic gesture, others suspect a cynical marketing ploy

Facebook has signed up almost half the countries in Africa - a combined population of 635 million - to its free internet service in a controversial move to corner the market in one of the world's biggest mobile data growth regions.

Facebook's co-founder and chairman, Mark Zuckerberg, has made it clear that he wants to connect the whole world to the internet, describing access as a basic human right. His Free Basics initiative, in which mobile users are able to access the site free of data charges, is available in 42 countries, more than half of them in Africa.