LASHKAR GAH - A journalist working for Afghan television station Ariana News was killed by a roadside bomb in the southern province of Helmand on Friday, his employer said, adding to a growing toll on media workers in Afghanistan this year. Witnesses said Nematullah Zaheer had been travelling with other journalists to report on a police operation just outside the provincial capital Lashkar Gah when their vehicle came under fire and police advised them to leave the main road.