Attacks killed three US soldiers in Afghanistan, NATO said Wednesday, the latest in a rising toll of foreign troops killed while battling insurgents who threaten to disrupt this week's elections. Two US troops serving in the NATO-led International Security Assistance Force (ISAF) were killed in a makeshift bomb attack in the southern province of Kandahar on Tuesday, a military spokesman said. Another soldier died in a "hostile incident" on Tuesday in the neighbouring province of Helmand, which is another Taliban flashpoint, the spokesman added. The deaths bring to six the number of NATO troops killed on Tuesday. Two US soldiers died in a bomb blast in eastern Afghanistan and a NATO soldier killed in a suicide blast in Kabul.