Rio+20: Progress on Earth issues 'too slow' - UN chief

Rio+20 - a major United Nations conference with more than 100 world leaders, has opened in Brazil, to chart a new more sustainable course of development.

It is 20 years since Rio hosted the Earth Summit, which spawned UN conventions on climate change, biodiversity and desertification, as well as the Agenda 21 blueprint for sustainable development.

At the Rio+20 conference, UN Secretary-General Ban Ki Moon warned that time is running out for the planet and complained that progress in the last two decades has been too slow.

David Shukman reports from Rio.