The Syrian army and its allies had advanced to within 10 km of Mayadin, Hezbollah War Media Center said Friday, bringing them close to a city seen as the current main base of the Wahhabi Daesh [Arabic acronym for "ISIS" / "ISIL"].
They have won control of positions and heights parallel to the main road linking Deir ez-Zor and Mayadin, located on the Euphrates in eastern Syria, the media unit said.
A war monitor, the so-called Syrian Observatory for Human Rights which is based in the UK, said on Thursday the army was only 6 km from Mayadin.
Daesh had staged fierce counter attacks in central Syria in recent days, testing the army's control of an area seized in a months-long eastward offensive.
Backed by Russian air power, the army has continued its advance towards Mayadin from Deir ez-Zor along the Euphrates valley.
In June, two US intelligence officials told Reuters that they believed Daesh had moved most of its diminished command structure and propaganda team to Mayadin, southeast of its former capital of Raqqa.
The Observatory said on Friday there were clashes in several areas in eastern Deir ez-Zor province. The Syrian military shelled Mayadin overnight and Syrian and Russian warplanes have conducted hundreds of strikes, it said.
Helped by the Russian military and allied forces last month, the Syrian army's advance to Deir al-Zor lifted a three-year-long siege imposed by Daesh on the city.
Daesh has lost swathes of territory to the Syrian government and to US-backed Syrian militias that are waging separate campaigns against the extremist group's last major strongholds in Deir ez-Zor province.
Source: News Agencies, Edited by website team