Syria conflict: UN's Staffan de Mistura hopeful

The UN mediator in the Syrian conflict, Staffan de Mistura, has told the BBC he believes there is a fresh opportunity to resolve the country's crisis.

He said truce measures may be favourable to moderate rebels and government forces as they face a common threat from Islamic State militants.

The UN has called for "freeze zones" to halt fighting and improve aid.

More than 200,000 people have died in Syria's increasingly fragmented civil war, now in its fourth year.

Lyse Doucet reports.