Police in the city of Maribor announced that they are conducting a probe into suspected smuggling of artefacts, after the three statuettes were found left behind in a tent at the Gruškovje refugee shelter near the border with Croatia on 4 November.

The National Museum has confirmed that the items are genuine ancient artefacts dating back to the Sumer civilisation and could be as much as 5000 years old.

No value has been placed on the items, although experts say that they could be priceless. Police are withholding publishing pictures of the statuettes for the time being.

With thousands of refugees from Syria, Iraq, Afghanistan and other countries passing through Slovenia at the time, the police are now trying to establish who could have been carrying the artefacts with them.

Analysis on the items which experts say are votive figures made of alabaster show they come from the ancient Mesopotamia region that stretches across modern day Syria and Iraq.

National Museum head of ancient history and geology Peter Turk told the STA that such finds are first checked with missing items from museums around the world contained in an Interpol database. "There are no stock keeping units on the artefacts, although these could have been removed."

Still, Turk thinks it more likely that the items are part of a personal collection.

Under Slovenian law, illegal smuggling of artefacts is punishable by up to five years in jail.

The first media outlet to report on the mysterious find was Radio Slovenia, which said on Tuesday that the statuettes may be connected with individuals who may have been looking to sell them on the black market as a way to start a new life.

Military operations have caused irreparable damage to thousand-year-old monuments in the Middle East and many valuable artefacts have been stolen and are now being sold on the black market.

A symposium discussing the issue was held in London at the end of last month. Participants said that severe damage to cultural heritage was being caused on the Turkish-Syrian border, where smaller artefacts in particular are being smuggled out of the country. Occasionally, parts of monumental art such as mosaics or larger plastics are also found among the smuggled objects.