Conditions of Dubai's immigrant workers highlighted

It is home to some of the tallest and most opulent skyscrapers in the world but behind Dubai's glittering facade, life for many of the people who helped build it, could not be more different.

Some migrant workers are facing destitution and are being prevented from returning home - a situation campaigners are calling "a form of modern day slavery".

From Dubai, the BBC's World Affairs Editor John Simpson reports.