Canadian and U.S. police are trying to unravel the mystery of how a human foot severed just above the ankle came to be among a stream of litter moving along a conveyor belt at a New York state recycling plant.

The origin of the appendage — a right foot, slightly decomposed and lacking a shoe or any other covering — is in dispute, with some reports suggesting it may be from Canada.

Police on this side of the border said yesterday morning the garbage from which the foot emerged came from a specific transfer station in the Toronto area. Staff Sgt. David Vickers also said other items that appeared to be medical waste were found in the same pile.

But authorities in the U.S. aren’t convinced.

Police there say most of the material that arrives at the recycling plant in the town of Seneca, midway between Rochester and Syracuse, N.Y., is from New York state. Only a small amount comes from Toronto.

“Somehow it got out there that the foot originated in Canada,” said Philip Povero, sheriff for Ontario County, N.Y.

The foot arrived with trash deposited sometime between July 29 and Aug. 3, Povero said. Since Wednesday, 136 recycling trucks have unloaded material at the plant next door to a landfill.