The Syrian military says it has “fully liberated” the eastern border town of Albu Kamal, so-called Islamic State’s last urban stronghold in the country.
Commanders said the victory signalled the “fall of the terrorist Daesh [IS] organisation’s project in the region”.
A monitoring group said militants had withdrawn to another part of Deir al-Zour province following negotiations.
IS now only controls a few villages and desert areas north of Albu Kamal, and scattered pockets elsewhere in Syria.
The jihadist group seized large swathes of Syria and neighbouring Iraq in 2014, when it proclaimed a “caliphate” and imposed its rule over some 10 million people.
But it has suffered a series of defeats over the past two years, losing Iraq’s second city of Mosul this July and its de facto capital of Raqqa in northern Syria last month.
The official Sana news agency quoted the Army Command as hailing the recapture of Albu Kamal as a “strategic achievement and a base for eradicating remnants of the terrorist organisations with its various names along the Syrian territories”.
The Syrian Observatory for Human Rights, a UK-based monitoring group, cited its sources as saying that Albu Kamal was retaken by troops and allied militiamen after the last militants in the town withdrew to areas in eastern Deir al-Zour.
Militias had agreed to open a corridor for the jihadists to leave, they added.
A military media unit run by Lebanon’s Hezbollah movement, whose fighters are supporting the Syrian army in the country’s six-year civil war, said army engineers were now combing Albu Kamal for bombs and mines.
On Wednesday, Syrian troops linked up with Iraqi forces on the border, giving the Syrian government control of its first official crossing with Iraq since 2012.
Last week, Iraqi forces secured the Iraqi side of the crossing after taking the nearby city of al-Qaim as part of an operation to clear IS out of its last pocket in Iraq.