BEIRUT — A Syrian war monitor says Islamic State militants have withdrawn from their last stronghold following a government offensive.

The Britain-based Syrian Observatory for Human Rights says government forces and allied troops, including Iraqi fighters, are combing Boukamal, a strategic town on the border with Iraq, on Thursday after ISIS militants withdrew.

Syrian pro-government media say Syrian troops had clashed with remnants of ISIS militants in the town after they entered it late Wednesday. On Thursday, they declared the town totally free of the militants.

The fall of Boukamal means remaining ISIS militants are currently holed up in small towns and villages along the border with Iraq and in the Syrian desert.