At least nine Syrian officers were killed during clashes with the Islamic State (IS) terror group, a media report said.The officers were killed during clashes on Saturday when the IS militants blew up a suicide car bomb near the Koerse airbase, Xinhua reported quoting the Syrian Observatory for Human Rights.The airbase has for long been besieged by the IS militants, who also repeatedly attempted to storm this crucial facility, but so far failed.Koerse, which has been besieged by the rebels since two years ago, is the biggest airbase in Syria, stretching on a five-square km land and including the Aviation Faculty, one of the biggest in the Middle East.