Valuable statues and cultural objects have been removed from Syria's National Museum in the capital, authorities report.
The theft was found on Monday, when staff apparently found that an entrance had been forced from the interior.
The six missing sculptures were made of marble and originated to the ancient Roman times, one official informed the news agency.
Syria's Directorate-General for Antiquities and Museums said it had launched a probe to identify the "details surrounding the theft of a group of exhibits", and that measures had been implemented to enhance security and observation methods.
The head of national security in Damascus province, General Osama Atkeh, was referenced by the government press as declaring that security forces were examining the theft, which he said had targeted several "historical artifacts and valuable objects".
He added that guards at the institution and other individuals were being questioned.
The cultural institution, which was created in 1919, houses the primary archaeological collection in the country.
It features historical records dating back to the ancient era from Ugarit, where indications of the earliest writing system was discovered; Greco-Roman period Greco-Roman sculptures from historical site, a significant cultural centres of the classical era; and a 3rd Century AD synagogue that was built at an ancient location.
The museum was forced to close in 2012, a year after the beginning of the internal strife. The majority of the holdings was transferred and preserved at undisclosed sites to safeguard them.
It partially resumed in recent years and completely reopened in early this year, a month after insurgents deposed the Assad regime.
Each of the six of Syria's Unesco World Heritage sites were affected or significantly impacted during the internal struggle.
The Islamic State group destroyed numerous religious structures and other structures at Palmyra, stating that they were against their beliefs. The cultural organization denounced the destruction as a violation.
Numerous artefacts were also lost or taken from archaeological sites and museums.
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