Syria army, allied militias retake IS stronghold Albu Kamal
The army said it had taken full control of Albu Kamal in the eastern province of Deir az-Zour which has changed hands several times.
Regime forces announced the capture of the town near the Iraqi border earlier this month but lost it to a blistering IS counter-attack a week ago.
"Syrian troops and allied forces took full control of Albu Kamal, and are removing mines and explosives left by IS," a military source in Deir az-Zour told AFP on Sunday.
"IS put up fierce resistance and tried to use explosives and suicide bombers, but besieging the city allowed the army to clinch the offensive and take full control of the city."
State news agency SANA also reported the advance in Albu Kamal, saying the "Syrian army and its allies eliminated the last Daesh (IS) terrorist pocket in the town".
A string of territorial defeats across northern and eastern Syria had left Albu Kamal as the last significant Syrian town held by IS.
Syria's army announced on November 9 it had ousted IS from the town, but the militants retook it in a lightning offensive.
A week later, the army and allied Iraqi, Lebanese, and Iranian fighters broke back into Albu Kamal and steadily advanced through the town.
The Britain-based Syrian Observatory for Human Rights, which has a network of sources across Syria, confirmed on Sunday that regime troops and their allies had captured Albu Kamal.
"IS fighters withdrew from the city towards the Euphrates River," Observatory head Rami Abdel Rahman told AFP.
"There is no more fighting in the town, but there are clashes around Albu Kamal," he said, adding that Lebanon's Hizballah, Iran's elite Revolutionary Guards and Iraqi militias had fought alongside regime troops, backed by Russian air power.
The monitor said more than 80 fighters were killed in the three days of ferocious combat to retake the town - 31 pro-regime forces and at least 50 IS militants.
IS seized large areas of both Syria and neighbouring Iraq in a lightning 2014 campaign, but this year has lost much of the territory it once held.
The loss of Albu Kamal caps the group's reversion to an underground guerrilla group with no urban base.