Canada released an interim report Tuesday on what happened when a U.S. jet accidentally bombed Canadian soldiers in Afghanistan, killing four and wounding eight, but the study contained little new information and portions had been withheld.

Retired Gen. Maurice Baril, who heads a Canadian investigation taking place at the same time as a separate U.S.-Canadian joint inquiry, cited security reasons for not releasing some parts of the report.

Baril told a news conference he submitted the interim report to defense officials including Defense Minister Art Eggleton, who decided what information about the April 18 accident could be made public.

Recent media reports said Baril had told relatives of the victims that Canadian forces had followed all proper procedures in conducting live training exercises that were bombed.

Baril declined to comment directly on those reports Tuesday at the news conference in Edmonton, Alberta, only confirming that he told victims' relatives that he was impressed by the professionalism of the Canadian forces involved.

The interim report made no mention of the pilot or flight crew of the U.S. F-16 fighter jet that dropped a 500-pound, laser-guided bomb on the Canadians conducting a live-fire night exercise near their base in Kandahar.

Baril said his investigating panel has requested permission to speak to the flight crew and pilot, but no answer has been received.

The final report of his investigation is due June 21, and Baril said he hoped more details could be made public then.

In Washington, Pentagon spokesman Bryan Whitman said the U.S. investigation of the incident is continuing and that no further details would be released until it was complete.

Baril praised U.S. military authorities for what he called unprecedented cooperation, including the handing over of all classified documents to the Canadian investigators.

"There are other findings that have been confirmed ... that at this point cannot be released," Baril said. "It's not because the Americans are not giving us the information. We have it all."