Islamic State group jihadists seized full control of the ancient Syrian city of Palmyra on Thursday, putting the world heritage site and its priceless artefacts at risk of destruction.
The Britain-based Syrian Observatory for Human Rights said IS now controlled half of all territory in the war-torn country.The capture of Palmyra, a former stopping point for caravans on the Silk Road, is the latest blow to efforts to hold back the advancing jihadists, following the fall of Iraq's Ramadi.
"IS fighters are in all parts of Tadmur, including near the archeological site," Observatory head Rami Abdel Rahman told AFP, using the Arabic name for the city.
The jihadists also proclaimed their capture of the entire city, which is strategically located at the crossroads of key highways leading west to Damascus and Homs, and east to Iraq.
The Observatory said regime troops had pulled back from positions in and around Palmyra, including from an army intelligence outpost, a military airport and a prison which the jihadists captured overnight.
The monitor, which relies on a network of sources on the ground, said IS now controls more than 95,000 square kilometres of Syria, which has been engulfed by a multi-sided civil war since a 2011 uprising.
'Regime troops collapsed'
The jihadists, notorious for demolishing archaeological treasures since declaring a "caliphate" last year straddling Iraq and Syria, fought their way into Palmyra on foot after breaking through in the city's north.
"Regime troops collapsed and withdrew from their positions without resistance," said Mohamed Hassan al-Homsi, an activist originally from Palmyra.
The assault on Palmyra came days after the militants took the Iraqi city of Ramadi, their most significant victory since mid-2014 when they conquered swathes of land, sparking a US-led air campaign to support Baghdad.
A US state department official said the loss of Ramadi would force Washington to take an "extremely hard look" at its strategy against IS.
The jihadists sparked international outrage this year when they blew up the ancient Assyrian city of Nimrud and smashed artefacts in the museum of Mosul, both in Iraq.
"The situation is very bad," Syria's antiquities chief, Mamoun Abdulkarim, said on Wednesday as IS overran the north of Palmyra.
"If only five members of IS go into the ancient buildings, they'll destroy everything," he added, calling for international action to save the city.Hundreds of statues and artefacts from Palmyra's museum have been transferred out of the city, according to Abdulkarim, but many others -- including massive tombs -- could not be moved.
On Wednesday, the Anbar police chief was dismissed, after video footage emerged online suggesting security personnel deserted their posts at the height of the IS offensive.
The militants' gains have sparked international concerns, with France pledging Wednesday to host high-level international talks next month in Paris over the threat posed by IS.
The US official said Washington would step up its aid to Iraq, including sending 1,000 anti-tank missile systems to help stop suicide car bombs and accelerating its training and equipping of tribal forces to fight IS.
"You'd have to be delusional not to take something like this and say: 'What went wrong, how do you fix it and how do we correct course to go from here?'," the official told reporters.
Asking not to be identified, the official highlighted the IS tactic of ploughing huge "vehicle-born improvised explosive devices" (VBIEDs) into buildings and walls.
In Ramadi, an explosives-packed bulldozer was used to blow up the security perimeter around a government-held compound.
Around 30 vehicles such as Humvees then flowed in, many loaded heavily with explosives.
Besides the more than 3,000 air strikes carried out so far, Washington has supported a deep reform of Iraq's army and offered training to Sunni tribesmen.
But that failed to prevent the loss of Ramadi, where Iran-backed militias will now take the lead in any counter-attack.
According to officials from Anbar, at least 500 people were killed in three days of fighting in Ramadi during which IS used waves of suicide car bombs.
Tens of thousands were forced to flee their homes in the process.
And on Wednesday, more than 2,000 were able to join them and escape conflict-torn Anbar after the authorities opened a bridge that had been closed for three days.