The Syrian army said the capital Damascus and its surroundings were fully secure for the first time in seven years after it cleared the last pocket of ISIS fighters from the city on Monday.
The captured areas included the Palestinian Yarmouk refugee camp in southern Damascus, which was the site of an intense barrel-bombing campaign by the regime of Syrian President Bashar Al Assad against rebels and civilians in the early years of the civil war that began in March 2011.
The camp was largely home to Free Syrian Army (FSA) opposition group fighters and Palestinian factions allied and opposed to Mr Al Assad's rule, prompting fierce clashes.
But after years of civil war, Syrian regime operations and incursions by militant groups into the camp, the population of Yarmouk, once as high as 160,000 people, has dwindled dramatically, with the void being filled by militants and trapped civilians.
"Damascus and its surroundings and Damascus countryside and its villages are completely secure areas," the army high command said in a televised statement, adding that the army would continue to fight "terrorism" across Syria.
If confirmed, the government of President Bashar Al Assad's control of Damascus and the surrounding areas would represent the first time the capital has been completely free of rebels and militants in almost seven years.
The Syrian military's claim would mean that Damascus and its suburbs are now in complete government control for the first time since the start of the Syrian civil war in March 2011.
It follows months of battles between ISIS fighters and Syrian government and allied troops in southern Damascus, leaving scores dead and leaving the already battered Yarmouk refugee camp an even greater scene of destruction.
ISIS had controlled the suburb of Hajar Al Aswad, located within Yarmouk, but Syrian regime officials said it had begun evacuating women, children and elderly people from the area on Sunday night. Some ISIS fighters were allowed to leave the Yarmouk camp and neighbouring area Al Tadamon.
ISIS now only controls several patches of desert territory in eastern Syria.
Its fighters burned their headquarters in Yarmouk before boarding buses with their relatives to leave the area, said Syrian Observatory for Human Rights (SOHR) chief Rami Abdel Rahman.
"The six buses left at dawn, heading east for the Syrian desert," he told AFP news agency.
Mr Al Assad has already ousted tens of thousands of rebels and civilians from areas around Damascus this year through military force and negotiated withdrawals, including the rebel bastion of Eastern Ghouta.
The regime used similar tactics to clear opposition towns northeast and south of Damascus earlier this month, leaving ISIS as the only armed presence in the capital.