Two more soldiers with the NATO-led International Security Assistance Force (ISAF) were killed Sunday in a bomb blast in Afghanistan's restive southern region, the ISAF said in a press release. "Two International Security Assistance Force service members died following an Improvised Explosive Device (IED) attack in southern Afghanistan today," the statement added. However, it did not disclose the nationalities of the ill-fated troopers and the exact place of the blast by saying "It is ISAF policy to defer casualty identification procedures to the relevant national authorities." Another NATO soldier was killed in a similar attack in the same region on Saturday. And two more NATO soldiers lost their lives in east Afghanistan on Friday. Within the framework of multinational ISAF, troops from the U.S. , Britain, Canada and Australia have been stationed in the Taliban stronghold of south Afghanistan to help stabilize that part of the post-Taliban country. The homemade IED and roadside bombings have proved the deadliest weapon for Afghan and NATO troops in the militancy-hit Afghanistan but the lethal devices have also claimed the lives of dozens of innocent civilians across the country. Over 530 troops with the NATO-led military alliance have been killed in Afghanistan so far this year.