The Art Newspaper has discovered that the largest and most powerful due diligence service used by the art world is at the center of three separate provenance disputes, two of which are working their way through international courts.

The Art Loss Register (ALR), a company founded by Julian Radcliffe that works with law enforcement officials worldwide, more than 80 auction houses, most major art fairs and innumerable collectors and dealers, has provided certificates confirming that works of art were free from claim, when they were in fact subject to claims by third parties or stolen.