Heavy clashes between Syria's army and the Islamic State group in Deir Ezzor city have killed at least 73 fighters in the last 24 hours. <br/><br/>The Britain-based Syrian Observatory for Human Rights monitor said, Syria's army controls most of Deir Ezzor city, capital of Deir Ezzor province in the country's east, and made further advances after responding to an IS attack that began on Saturday. <br/><br/>The monitor said the fierce fighting killed at least 50 IS fighters, as well as 23 Syrian soldiers and pro-regime militiamen. <br/><br/>Observatory Director said government forces had captured two new neighbourhoods and the municipal stadium.