Syrian regime forces on Friday took full control of Deir Ezzor from the last Daesh militants in the city after two-month campaign backed by Russian air power, regime television reported.
The city's fall marks another key defeat for Daesh, who have recently lost most of the territory they seized in their 2014 advance across Syria and Iraq.
"The armed forces, in cooperation with allied forces, liberated the city of Deir Ezzor completely from the clutches of the Daesh terrorist organisation," a regime source said.
Daesh had besieged a regime-held enclave in the city for four years until regime forces relieved it in early September.
A battle for Daesh-held parts of the city then ensued.
The regime captured the Al Hamidiya, Sheikh Yassin, Al Ardhi and Al Rashidia districts of the city in recent attacks.
The Al Hawiqa district was the last to be held by Daesh, a military media unit run by the regime's ally, Hezbollah reported.
TRT World's Sara Firth reports.
Deir Ezzor, on the west bank of the Euphrates, is the largest and most important city in eastern Syria. It is the centre of Syrian oil production.
After Syria's uprising broke out in 2011 with anti-regime protests, rebel groups seized parts of Deir Ezzor and the surrounding province.
But in 2014, as Daesh rampaged across Syria and Iraq, it seized the territory held by rival groups and rebel forces in the province and closed in on Deir Ezzor city.
By January 2015, Daesh had seized parts of the city and imposed a siege on regime forces and civilians.
Humanitarian crisis
Estimates of the number of people living in Deir Ezzor vary, but all agree that the population of the city has shrunk dramatically from its pre-war figure of 300,000.
The United Nations said earlier this year, before the siege was broken, that more than 90,000 people remained in areas under regime control.
The siege created food shortages, sent prices soaring and limited access to medicine and healthcare.
The UN began airdropping aid into the city in April 2016, but the programme was briefly suspended after a Daesh advance in January which overran the aid-drop zone.
Activists have also reported dire humanitarian conditions in Daesh-held territory, particularly as regime forces neared, cutting supply routes.
