VAUGHAN, Ont. -- Authorities are to announce details today of a years-long investigation into what they describe as an Ontario-based online "big box store" for child pornography.

Provincial police say they collaborated with the Toronto Police Service and the U.S. Department of Homeland Security on the investigation, which has culminated in numerous arrests.

They say nearly seven years of work has led them to take down the operation.

Officers allege the online store was providing photos and videos of child pornography to thousands of paying customers around the world.

Police say they've laid unprecedented criminal charges in the case.

A news conference announcing details of the probe and the charges is to get underway in Vaughan, Ont., at 11 a.m.