A new book by retired Canadian lieutenant-general Romeo Dallaire slams the United States, Britain and France for convincing the United Nations to ignore the 1994 genocide in Rwanda, which saw 800,000 people murdered.

"Ultimately, led by the United States, France and the United Kingdom, this world body (the UN) aided and abetted genocide in Rwanda," Dallaire writes in the book.

"No amount of its cash and aid will ever wash its hands clean of Rwandan blood."

It's been almost 10 years since Dallaire was head of the UN Assistance Mission for Rwanda. Shake Hands with the Devil: The Failure of Humanity in Rwanda details how his pleas to UN headquarters for reinforcements were ignored before the horrifying genocide took place.

The former peacekeeper also rebukes the U.S. and France for their failures.

"The UN and the secretariat are small-time culpable compared to the U.S. and France and their actions and inactions," Dallaire said in an interview with The Globe and Mail.

He said France and the U.S. were "dominated by self-interest and the psychology of still having imperial, colonial traits."

Using detailed daily notes taken by an assistant in Rwanda, Dallaire chronicles how a Hutu majority launched a ferocious attack on Tutsis and Hutu moderates.

Among the horrors Dallaire describes in the book: picking his way over stacks of bodies clogging a creek, and walking in front of his vehicle to move pieces of bodies out of the way.

He also frankly describes his sometimes public struggle with post-traumatic stress disorder -- a result of what he witnessed in Rwanda.

"People thought maybe writing it was going to be therapeutic, but I don't think it really was," he told The Globe.

"The only positive aspect is that I don't have it all in my head anymore. The book is 600 pages, but I wrote a couple of thousand pages, and a lot of the weight in having it all in memory -- it's taken away a lot of pressure."