A United Nations International Organization for Migration official expressed concerns Friday over the disappearance of thousands of Europe-bound immigrants who were intercepted and returned to Libya, fearing that many of them could have ended up in the hands of criminal groups and traffickers, while others were being extorted for release.

According to the spokeswoman for the International Organization for Migration, Safa Msehli, the Libyan coast guard intercepted more than 24,000 Europe-bound migrants in the Mediterranean so far this year, including over 800 this week alone.

However, only 6,000 have been accounted for in official detention centers in the North African country, Msehli said, adding that the fate and whereabouts of thousands of other immigrants remain unknown.

IOM says the number of immigrants intercepted and returned to Libya till August of this year is more than double the number for 2020, when more than 11,890 were brought back to Libya’s shores.