WASHINGTON/KABUL - Three American soldiers were killed by an improvised explosive device in southern Afghanistan on Friday, US defence officials said.

NATO had earlier indicated that the service members — working under the alliance’s International Security Assistance Force — and a dog were killed in the Taliban attack in the southern province of Helmand.

Meanwhile, a suicide bomber in western Kabul targeted top High Peace Council advisor Mohammad Massom Stanikzai on Saturday, police said, killing one civilian and injuring several others.

Stanikzai escaped unharmed, but a black armored car was damaged in the bombing, according to a Reuters witness. The incident was under investigation according to police. Severals protests in Kabul are planned to take place later on Saturday in support of presidential candidate Abdullah Abdullah’s decision to drop out of the race over allegations of mass fraud. He has called for the electoral bodies to halt counting votes and suggestd the United Nations intervene. The move imperilled Afghanistan’s political transition at a critical time, as most foreign troops will leave by the end of 2014 after 13 years of war.