John Simpson speaks to Syrian rebel leader Col Riyad al-Asad

Tracking down and interviewing Colonel Riyad al-Asad close to Turkey's border with Syria is not an easy business.

The colonel's name sounds close to but not quite the same as that of the President he wants to overthrow, Bashar al-Assad.

He is based in a refugee camp at Apaydin, very close to the Syrian border. But he is not allowed to leave the camp, and cannot receive visitors.

John Simpson reports.