Is China building on disputed Spratly Islands reefs?

A chain of islands in the South China Sea has become the centre of a territorial dispute - and a source of growing tension in the region.

The Spratly Islands are situated in a key shipping route, surrounded by natural resources.

A number of neighbouring countries claim ownership of the island chain but China has a new way of pressing its territorial claim.

Rupert Wingfield-Hayes reports from the Gaveen reef.