US President Barack Obama has apologised over the burning of Korans at a US airbase in Afghanistan, where three days of protests have killed 14 people.

Afghan police have shot and killed three protesters in two separate incidents as riots broke out during demonstrations over this week’s Koran burning incident.

Amnesty International said it had directly appealed to the Taliban to free 21 South Korean hostages, warning the militant movement that holding and killing captives was a war crime.

A roadside bomb hit a convoy of Nato peacekeepers in north-eastern Afghanistan on Friday, damaging one vehicle but hurting no one, an official said.

British troops are making final preparations for their new security role in Afghanistan aimed at tackling the lawlessness that still dominates large parts of the country.