Islamic State militants are in full control of the famed archaeological site in the ancient town of Palmyra in central Syria, according to activists.
The extremists overran the site to the south-west of the town shortly after midnight, said Rami Abdurrahman of the Britain-based Syrian Observatory for Human Rights.
Bebars al-Talawy, an activist in the central province of Homs, also said IS controls the ruins at Palmyra, a Unesco world heritage site famous for its 2,000-year-old Roman-era colonnades and other ruins and priceless artefacts.
Both activists said IS has not damaged the ruins so far.
There are fears the extremists will destroy the ruins as they did major archaeological sites in Iraq.
The capture of Palmyra was a major triumph for the militant group, days after it took the strategic city of Ramadi in Iraq's largest Sunni province.
As IS took Palmyra, government forces collapsed in the face of the attacks and Syrian soldiers were seen fleeing the area, activists said. In Damascus, state TV acknowledged that pro-government forces had withdrawn from the town.
The ruins at Palmyra are one of the world’s most renowned historic sites. Before the war, thousands of tourists a year visited the remote desert outpost, a cherished landmark referred to by Syrians as the “Bride of the Desert”.
Many Palmyra residents are fleeing the town towards the city of Homs and Damascus, according to Talal Barazi.
Mr Barazi, governor of the central province of Homs which includes Palmyra, said the Syrian army is outside the town, from where it is targeting IS reinforcements.
“We have not received any news about (the archaeological site’s) destruction,” he said. “We hope that there will be no massacres in the city or damage to the ruins.”
Palmyra has a population of 65,000 people, according to Mr Barazi. He added that 1,300 residents had fled over recent days and more are trying to leave.
In taking the town, IS also overran Palmyra’s notorious Tadmur prison, where thousands of Syrian dissidents have been imprisoned and tortured over the years.
A video posted online showed IS fighters setting alight a giant poster of president Bashar Assad, cheering as flames rose around them against the night sky.
Mr al-Talawy said the government had recently transferred thousands of detainees from the Palmyra prison to a jail near Damascus.
But he added that IS extremists freed some of those still inside by the time they captured the prison. He could not provide any definitive figures but there were believed to have been thousands still there.