this is outside source live from the bbc newsroom. our lead story is g20 leaders of the world's richest nations pledge more aid to afghanistan which is facing economic collapse. that g20 summit on afghanistan comes as turkish authorities boost security on their border with iran — and warn they won t accept an influx of people fleeing the taliban in afghanistan. many afghans make the journey through iran to turkey — hoping to travel onwards to other european countries. turkey already has the world s largest refugee population — of around four million people. our international correspondent orla guerin has been to the turkish border province of van and sent this report. turkey is cracking down. on those