LONDON — The old file he was reading contained the slightest whiff of his office in Rwanda, but for Romeo Dallaire the minute odour brought back the stench of death that enveloped him 10 years ago.

"It stayed in the paper," he recalled of a moment that stopped him cold as he worked on his book, Shake Hands with the Devil - the Failure of Humanity in Rwanda. "It took over three weeks and a lot of convincing by my therapists to get me back at the book, because the odour in the office was the prevailing odour of death. I mean, it was all over. It was sort of glued to the page."

Hailed for his courage in trying to prevent the slaughter of more than 800,000 men, women and children in Rwanda, Dallaire has had his health blighted by the genocide he witnessed a decade ago.

But now, he is back to the point where he can function normally, something he partly attributes to writing the book, which helped shake some of the demons that have tormented him over the last 10 years.

"I will never be what I was," Dallaire said in a recent interview at Canada House in London while en route to the Rwandan capital of Kigali to mark the 10th anniversary of the genocide at a ceremony on Wednesday.

"I'll never be able to achieve that, but I believe I am at a level where I can function quite reasonably."

Dallaire, 57, has accepted a fellowship at Harvard starting in September, where he will write about conflict resolution. He also works as an adviser to the Canadian government on war-affected children and child soldiers.

Dallaire was force commander of the UN Assistance Mission for Rwanda in 1994 when what was thought to be a civil war became much more sinister.

In a 100-day period after the president's plane was shot down, Rwanda's Hutus tried to wipe out the minority Tutsi population. Although the majority of those murdered were Tutsis - many hacked to death with machetes - politically moderate Hutus and others were also massacred.

Dallaire repeatedly told the UN that he needed more troops and a change in his orders to allow those under his command to use force to stop the slayings.

But the UN didn't take notice and cut its peacekeeping force of about 2,500 soldiers. If the multinational contingent had been doubled instead, Dallaire is confident he could have prevented the bloodbath.

Dallaire's time was in demand during his stay in London. He has just finished an interview with a Dutch television station, an appointment that overran its allotted time by at least 45 minutes, but Dallaire patiently plows on with his schedule.

Dressed in a grey suit, his Order of Canada pin on his left lapel, Dallaire leans forward from the couch where he is seated when he wants to emphasize a point, which he does when he lays blame for Rwanda at the feet of Britain, France and the United States.

Dallaire is convinced that the three permanent members of the UN Security Council had all the intelligence they needed to act in Rwanda but chose to do nothing.

"This was simply a low-priority exercise to which no one had any interest. They were up to their ears in Yugoslavia and Cambodia and God knows what else," he said.

In January, Dallaire testified at the UN Criminal Tribunal for Rwanda, where lawyers for the men accused of genocide and crimes against humanity tried to portray Dallaire's recollection as muddled because of the post-traumatic stress he suffered.

Dallaire describes his experience at the tribunal's hearings in Tunisia as gut-wrenching, especially seeing Col. Theoneste Bagosora, who is accused of masterminding the slaughter when he seized control of the country after the president's death on April 6, 1994. Bagosora denies the charges.

Dallaire said preparing to see Bagosora was his third descent into hell. The first was witnessing the genocide and the second writing the book, which was published last fall.

At times, Dallaire said he wanted to walk away from the book, but he was persuaded to keep at it by Maj. Brent Beardsley, who served with him in Rwanda.

Beardsley told him that without the book, his grandchildren would never know the truth of what happened in Rwanda.

"That argument was exceptionally strong," said Dallaire, who is married and has three grown children.

But after a suicide attempt and a series of mental breakdowns, Dallaire wasn't sure he would be able to complete the project.

"I was very fearful that papers and also my memory would be affected because of the medications and stuff like that, and so it would never be written and would die with me," he explained.

UN Secretary General Kofi Annan, who was responsible for UN peacekeeping in 1994, recently paid tribute to Dallaire for his desperate attempts to get more soldiers sent to Rwanda.

"There was more that I should have done to sound the alarm," Annan said in a message to a conference on the genocide in London that included Dallaire among the featured speakers.

"The political will was not there and neither were the troops."

Ten years later, Dallaire doesn't think the world would react much differently if another Rwanda were to emerge.

He isn't completely pessimistic about the future, however. Remembering a starving young boy he helped in Rwanda whose entire family was wiped out in the genocide, Dallaire explains his hope.

"We will ultimately eliminate conflict due to our differences, because ultimately we will realize that we are exactly the same," he said. "The three-year-old Rwandan kid on that road was absolutely no different from my three-year-old. They were both human children.