“The Syrian army and its allies break the siege on Deir ez-Zor,” a media unit run by Hezbollah said, Reuters reported.
State television and the so-called Syrian Observatory for Human Rights also reported that advancing Syrian forces had linked up with government troops in Deir ez-Zor.
The army and its allies had made lightning advances in recent days and pushed through Daesh lines to within kilometers of Deir ez-Zor.
Deir ez-Zor is located southeast of Daesh’s main stronghold Raqqa.
Both cities lie in oil-rich areas on the Euphrates River.
Syria has been gripped by civil war since March 2011 with various terrorist groups, including Daesh, currently controlling parts of it.
According to a report by the Syrian Center for Policy Research, the conflict has claimed the lives of over 470,000 people, injured 1.9 million others, and displaced nearly half of the country’s pre-war population of about 23 million within or beyond its borders.