More than 50 people have been arrested in a global investigation into the trafficking of cultural goods.
The operation has seen more than 9,400 objects recovered across the world.
Recovered items include archaeological objects, furniture, coins, paintings, musical instruments and statuettes.
Operation Pandora VI has seen law enforcement authorities in 28 countries carry out checks and controls at airports and border crossing points, as well as in auction houses, museums and homes.
Special focus was placed on monitoring online markets. A “cyber patrol” week was held in the Netherlands to identify suspicious sales online.
In France, Customs seized 4,231 archaeological objects. These included 3,000 coins, bells, buckles, rings and pieces of pottery, which officials say were looted from sites by one person, using a metal detector.
French Customs also seized three ancient statuettes dating back to the La Tolita-Tumaco pre-Columbian culture in Ecuador.
Spanish police recovered a treasure trove of 91 gold coins from the Roman Empire, with an estimated value of €500,000 on the black market.
That investigation began after the coins were detected in a well-known auction house in Madrid and investigators were able to identify the Spanish archaeological site from where they had been looted from.
In the US, Customs officers seized a shipment containing 13 pieces of ancient Mexican artefacts from the Post-Classic to Aztec era — a period of more than 600 years from around 900 — including a skull and 12 adze chopping tools.
A processional cross dating from the 13th century was recovered by Romanian Police and returned to the Evangelical Church Museum of Cisnadie, from where it had been stolen in 2016.
The object had been recorded in Interpol's Stolen Works of Art database and was identified via the ID-Art app.
The art and antiques crime unit in the Netherlands recovered two paintings by 20th-century artist Kees Verwey that had been reported stolen. They were recovered following checks on an online sales catalogue involving an Amsterdam auction house.
Officers from Greece also recovered a marble column dating back to the Roman period, alongside 13 ancient coins and three pottery vessels dating back from the Hellenistic period, a period of almost 300 years that began in 323BC.
In raids on properties, 90 metal detectors were seized.
More than 170 investigations are ongoing and more seizures and arrests are anticipated.
Operation Pandora VI is being led by the Spanish police in co-operation with Interpol and Europol and the World Customs Organisation.
Launched in 2016, Operation Pandora is an annual law enforcement operation. It has resulted in 407 arrests and the recovery of 147,050 cultural artefacts.