The culture of Britain’s youth faces being “shaped and defined” by American giants such as Facebook, Amazon and Netflix, the BBC fears, as it announces major investment in children's television.

The BBC has confirmed it will invest £34 million in expanding digital programming for children, as it attempts to win their attention in a changing online world.

In a speech to staff, Lord Hall, the director-general, will spell out how the BBC must “reinvent” its offering to its youngest audience in the coming years, moving beyond television programmes to become a serious rival to “global media giants”.

In the BBC’s first Annual Plan, released today and setting out the corporation’s ambitions for the coming year, Lord Hall and chairman Sir David Clementi will announce the “biggest investment in children’s services in a generation”.