Opposition factions on a lightning advance through Syria said on Saturday they have begun to encircle Damascus as government forces denied they had withdrawn from areas near the capital.
"Our forces have begun the final phase of encircling the capital, Damascus," said opposition commander Hassan Abdel Ghani.
The defense ministry flatly denied the army had fled positions near the city, according to AFP.
"There is no truth to news claiming our armed forces, present in all areas of the Damascus countryside, have withdrawn," it said.
Earlier, a war monitor and Abdel Ghani said opposition fighters were within 20 kilometres of Damascus as government forces fall back in the face of the offensive gathering even more momentum.
The Syria Observatory for Human Rights said government forces had ceded more key ground, losing control of all of southern Daraa province and evacuating posts in Quneitra, near the Israel-annexed Golan Heights.
The monitor said government forces were also pulling out of towns as little as 10 kilometres (six miles) from Damascus.
Abdel Ghani said earlier that "our forces were able to control the Saasaa (security) branch in the Damascus countryside. The advance towards the capital continues."
Airstrikes and shelling by government forces and their ally Russia killed at least seven civilians near the city of Homs, as the army sought to slow the opposition advance there.
The opposition gains have brought Hayat Tahrir al-Sham (HTS) and its allies to the doorstep of President Bashar al-Assad's seat of power, just over a week into a renewed offensive in a conflict that had long seemed frozen.
As the militants seize more territory, they have also sought to reassure those living in areas now under their control.
Abdel Ghani in a statement on Telegram Saturday recognized that the opposition had taken areas where "different religious sects and minorities" live.
"We ask that all sects be reassured... for the era of sectarianism and tyranny has gone away forever," he said.
Minorities have often been persecuted during Syria's long conflict, and HTS's precursor Al-Nusra Front, which was linked to Al-Qaeda, launched deadly attacks on Assad's Alawite minority in Homs early in the war.
The army said it was redeploying in the south where the Observatory said the government had lost control of Daraa province and the key city of the same name, cradle of the 2011 uprising.
An AFP correspondent in Daraa saw local fighters guarding public property and civil institutions on Saturday.
In the central Homs area, a key stepping stone to the seat of power in Damascus, the Observatory said government forces had brought "large reinforcements" and stopped the opposition advance.
An army statement carried by state media said government forces were "redeploying and repositioning" in the southern provinces of Sweida and Daraa.
But both the Observatory and opposition said that government forces no longer controlled any of Daraa province.
Daraa and Quneitra are near the Israeli-annexed Golan Heights, where Israel said it was boosting its troop presence, and Jordan, which late Friday urged its citizens to leave Syria "as soon as possible".
Russia and the United States have also advised their nationals to leave.
For his part, US Secretary of State Antony Blinken called for a "political solution to the conflict" and for the protection of civilians and minorities, his spokesperson said Friday, in a call with Turkish Foreign Minister Hakan Fidan.
Fidan and his Iranian and Russian counterparts discussed Syria in Qatar on Saturday.
Qatar's prime minister, Sheikh Mohammed bin Abdulrahman bin Jassim Al-Thani, said the world had been "surprised" by the speed of the opposition advance, and called for "a political framework" to prevent violence from spiralling.
He also said Assad had failed to "start engaging and restoring his relationship with his people".