Western collectors are thought to be in direct contact with Islamic State looters, who have taken millions of pounds worth of artefacts from ancient churches across Iraq and Syria, it has been claimed.
President of the Belgian federal police council, Willy Bruggeman, told The Times that ISIS are "using their own networks to come into contact with the final buyers...they want to have a one-to-one relationship with the collectors".
Bruggeman also said that some looted goods had almost certainly been sold to UK buyers, though none have as yet been traced.
Goods are most likely smuggled across the borders using the same illegal channels as oil and arms. ISIS has secured huge amounts of money from oilfields in eastern Syria, and has also pillaged ancient sites – taking priceless antiques from monasteries and churches, among other sites.
A senior Iraqi intelligence official told the Guardian in June that militants had taken $36million, around £23million, from the al-Nabuk area – a mountainous region west of Damascus – alone.
The group has specifically targeted Christian sites, and Bruggeman confirmed that murals and masonry ripped from church walls are among the most commonly traded artefacts. ISIS doesn't just steal, but also usually entirely desecrates religious sites. A fourth-century Syrian monastery was seized by insurgents in July, and militants also destroyed a tomb thought to be that of biblical prophet Jonah.
Bruggeman said the attack of religious sites is a means by which ISIS can "undermine the morale of the communities they invade".
"You...see a kind of cultural cleansing," he said.
Last week, it was revealed that churches in Qaraqosh, Iraq, are being used as torture chambers by Islamic State militants.
Abu Aasi, told The Sunday Times that Bahnam Wa Sara and Al Kiama churches in Qaraqosh were being used to hold and torture prisoners.
"Most inside are Christians and they are being forced to convert to Islam," Mosul priest Abu Aasi said.
"Isis have been breaking all the crosses and statues of Mary."