MONTREAL - A defence lawyer at a landmark Canadian trial stemming from the Rwandan genocide is challenging the memory of former general Romeo Dallaire.

Dallaire, the former head of a doomed United Nations peacekeeping mission in Rwanda, is testifying Wednesday at the war crimes trial of Desire Munyaneza.

Defence lawyer Laurence Cohen asked Dallaire if the trauma of his time trying to keep peace amid the massacre of some 800,000 Rwandans might affect his memory.

Dallaire says his post traumatic stress disorder has actually forced him to relive many events in vivid detail.

Under defence questioning, Dallaire admitted he was a neophyte at international field command when he took on the UN mission in 1993, despite more than 30 years in the army.

Munyaneza, a former Toronto resident, is accused of leading a rampage of rape and murder in the Butare region of Rwanda in 1994.