Three detainees alleged to have been physically abused by Canadian soldiers have disappeared while in Afghan custody, according to a report.

Investigators said they do not know what happened to three men who were handed over to the Afghan national police on April 8, 2006, said Maj. Robert Bell, a senior operations officer for the Canadian National Investigation Service, in an interview for the Globe and Mail.

NIS investigators have been trying to find the men for almost a month. They were picked up near the village of Dukah, 50 kilometres west of Kandahar on April 7, 2006.

Poor record-keeping by Afghan guards or undocumented release, which occurs regularly and often as a result of bribes, could explain their disappearance. But they may have been tortured or killed.

Human rights groups have complained that under a detainee agreement with Afghanistan, Canada can't monitor detainees after they have been handed over and can't ensure that they will not be tortured or even executed in Afghan prisons.

Afghan authorities have a reputation for torture.

But last week, another agreement was signed on transferring prisoners. Canada now has to notify the Kandahar manager of the Afghanistan Independent Human Rights Commission when it transfers a prisoner, along with the International Committee of the Red Cross.

According to a law professor at the University of Ottawa, based on National Defence documents he obtained under the Access to Information Act, the three men suffered injuries to their faces, heads and upper bodies. They had swollen eyes, cuts on their eyebrows, gashes to their forehead and slashes on their cheeks.

Prof. Amir Attaran said the documents were based on handwritten reports from Canadian military police in the southern Afghan city of Kandahar.

He said the injuries appear to have been inflicted while the men were in Canadian custody — an allegation the military denies but is investigating.

With files from the Canadian Press