At the same time, the Syrian Observatory for Human Rights said fighters from the powerful Lebanese Shiite movement Hezbollah, who had spearheaded the regime's assault, were in control of the town.
Control of Qusayr was vital for the rebels as it was their principal transit point for weapons and fighters from neighbouring Lebanon.
It is also strategic for the regime because it is located on the road linking Damascus with the coast, its rear base.
"Yes our brothers, this a round that we have lost," the General Commission of the Syrian Revolution said on its Facebook page, but rebels seeking to oust President Bashar alAssad "will continue to fight the thousands of Lebanese mercenaries."
That was a reference to Hezbollah, a close ally of Assad's regime.
Earlier, Syria state television said the army "totally controls" the strategic region of Qusayr after an offensive against rebel fighters that lasted almost three weeks.
"The Syrian army totally controls the Qusayr region in Homs province after killing a large number of fighters and capturing others," the report said, using the regime's terminology for the rebels.
The Britain-based Observatory, which relies on a network of activists and medics on the ground, also confirmed that Qusayr had fallen.
"The army and Hezbollah have succeeded in taking Qusayr after an intense bombardment of the town overnight," it said. "The rebels have withdrawn to other areas because they were short of ammunition."
Official news agency Sana said the army had "reestablished total security in the town of Qusayr," while Hezbollah's alManar television, which has a correspondent on the ground, said the rebels had fled north toward the nearby villages of Dabaa and Buweida alSharqiya.
The Observatory said fighting continued in Dabaa and in Buweida alSharqiya, the last village under rebel control in the area.
SANA said regime forces had seized a number of tunnels where rebels had been hiding, and that "they surrendered in large numbers."
It also said troops, who were "continuing to scour the town," had "defused dozens of bombs the fighters had placed in houses and the streets to block the army's advance."
Assad forces and Hezbollah fighters launched an offensive on May 19 to retake the Qusayr region, which abuts the Lebanese border.
Rebels fighting to retain control of the town, only some 10 kilometres from the frontier, were later joined by hundreds of reinforcements from Lebanon, most close to the Muslim Brotherhood.
That lead to pitched battles in which civilians, many of them wounded, became trapped.
Doctors had appealed for the Red Cross to be allowed in to treat the wounded, but Syrian officials said this would only be permitted once the rebels had been defeated.
Civilians who had managed to flee Qusayr described it as "a ghost town, heavily damaged and filled with the sound of bombs," the UN refugee agency UNHCR said on Tuesday.
Those who had escaped were mainly women and children, because men risked being killed at checkpoints, said spokeswoman Melissa Fleming.
COMMENTS (3)
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ
Proxies of Qatar/Saudis/USA/UK/France/Turkey defeated by the proxies of Iran/Russia. Meanwhile the Syrian people continue to suffer as their country becomes the next battleground in this brutal regional realpolitik.
Mujaideen Allah are with you--- lost of Quysar is not the lost of faith. Those mujaiden shaheed are defender of true Islam . So keep doing Jihad..Theire are betrayter in umah who betryed muslim in Afganistan, Iraq and now in syria. all infidels are united iran, hizbusatan, Israel, Russian and US
Allah Bless you from Pakistan
Well done Syrian Army and Hizbullah... You have done very wonderful and great job....Kill the puppets of America/Saudi Arabia/Qatar and Istreal......they are using Terrorists all across world to destroy Syria in the name of Islam but Hizbulla and Syrian army did very good job to destroy the terrorists belong to American Islam...
Hatts off Assad Army and Hizbullah.....
You are bravo and true followers of Islam e Muhammad (PBUH)