Afghan software entrepreneur Farshid Ghyasi, chief executive of the Netlinks company, is struggling to keep his best employees, as more plan to join a wave of migrants leaving for Europe that risks causing long-term damage to the country and its economy.

He is not alone in bemoaning the mass exodus, triggered by poor job prospects and worsening security as Taliban insurgents grow more powerful after the bulk of NATO troops withdrew at the end of 2014.

Many of those going are young city dwellers who should be spending their productive years at home as their country struggles to emerge from war, and nearly 15 years of international support, to build a self-sustaining economy.