Wal-Mart, the world’s largest retailer, said on Tuesday it was asking its suppliers to stop using cotton from Uzbekistan, joining a boycott by global brands over its use of forced child labour during the cotton harvest. It is the first time the retailer has taken such sweeping action over sourcing issues, reflecting its push over the past three years to improve its record on social and environmental sustainability under Lee Scott, its chief executive...The retailer’s move, which follows similar steps by retailers in Europe, was welcomed by a coalition of ethical investment groups that have been campaigning for US companies to apply pressure to Uzbekistan.