Government-backed militia set up a series of roadblocks with the intent to separate and slaughter Tutsis during the 1994 Rwandan genocide, former general Romeo Dallaire testified Tuesday.

"It was simply there as a tool of ethnic cleansing," Dallaire said of the maze of roadblocks. "There was no military or technical value. It was purely to destroy human beings."

Dallaire, the former commander of United Nations peacekeeping troops in Rwanda in 1994, spoke at the war crimes trial of Desire Munyaneza.

Munyaneza, who now lives in Toronto, is on trial for two counts of genocide, two counts of crimes against humanity and three counts of war crimes.

He is alleged to have been a militia commander during the 100 days of genocide, during which between 800,000 and one million Tutsis and Hutu moderates were massacred.

He was detained by the RCMP in 2005, and was charged with genocide, crimes against humanity and war crimes. He was the first person to be charged under Canada's Crimes Against Humanity and War Crimes Act.

Dallaire headed the UN mission to keep peace in Rwanda after the turbulent civil war broke out.

He did not testify specifically about Munyaneza's involvement, but painted a broader picture of the scope and organization of the massacre.

Dallaire's testimony outlined the context that could elevate the alleged crimes from rape and murder to genocide.

Dallaire said that targeted rape and murder spread across Rwanda at the hands of the Interahamwe militia, a unit of which several other witnesses said Munyaneza was a leader.

He described finding piles of half-burnt Tutsi identity cards at the scene of massacres, and detailed tactics used by Hutu extremists to massacre Tutsis and Hutu moderates.

Hundreds of Tutsis would be tricked into seeking refuge inside churches where they would be kept and slaughtered over several days, he said.

During his testimony, the former general also described an atmosphere of distrust between Rwanda's Hutu government and the Rwandan Tutsi rebels during talks to establish an interim government leading up to the war.

Now 61, Dallaire said he was dealing with poorly trained soldiers while he was in charge of the failed UN peacekeeping mission. He said the peace accords that were supposed to end the 1993 Rwandan civil war imposed an impossible deadline on his mission.

He told the court that when he finally arrived in October 1993 and launched the mission with three officers, he already had the sense time was running out.

A coup in neighbouring Burundi had sent 300,000 refugees into Rwanda, adding to instability. About 2,100 troops, mostly from Bangladesh and Ghana, arrived over the next five months. But he said they were mostly poorly equipped, ill-trained and unable to sustain themselves for two months.

"The first question the Bangladeshis asked was, 'Where do we eat?'" Dallaire testified.

"When hostilities resumed in April (1994) the Ghanans' equipment was still on a ship,'' he added. "They didn't even have a vehicle."

The Canadian called for more international troops to intervene, warning of an impending blood bath, but his requests went unheeded. Rather than boost the troops' commitment, the UN evacuated much of Dallaire's force, leaving him with only a few hundred troops when the slaughter was at its peak.

The massacres erupted on April 6, 1994 after Rwandan president Juvenal Habyarimana died when his plane was believed to be shot down.

Dallaire sunk into depression after his self-described failure, and was eventually discharged for medical reasons. He has said he hit rock-bottom and even attempted suicide several times.

He said he eventually got his life back together through a combination of therapy and medication, writing a book about his experience -- "Shake Hands With the Devil" -- and becoming an advocate for military intervention in humanitarian causes.

He has also taken a public stand against the use of child soldiers.

Dallaire has been the subject of a documentary by Toronto filmmaker Peter Raymont, as well as a feature film starring Quebec actor Roy Dupuis. Both were titled "Shake Hands With the Devil."

Dallaire is now a Canadian senator.

With files from The Canadian Press