Canada's parliament has unanimously passed a motion calling on Japan to apologise for forcing some 200,000 women to serve as wartime sex slaves.
Surviving victims still demand an apology more than 60 years on
The motion sponsor, opposition MP Olivia Chow, said the episode constituted "crimes against humanity".
The women affected were mainly Chinese, Korean, and Filipina, but other nations have demanded Japan apologise.
In 1993 Japan issued an official apology over so-called "comfort women", but parliament never approved it.
Former Prime Minister Shinzo Abe caused uproar earlier this year when he said there was no proof of state involvement - a statement he later played down.
'Formal and sincere'
The symbolic, non-binding Canadian motion calls on Japan to "take full responsibility for the involvement of the Japanese Imperial Forces in the system of forced prostitution".
Many victims hid their past for years out of shame
It must offer "a formal and sincere apology expressed in the Diet to all of those who were victims".
Japan said it regretted the vote, and it would not help bilateral relations.
Similar motions have been adopted in the US and the Netherlands.
Speaking to the AFP news agency after the vote, Ms Chow said: "For me, this isn't crimes against 200,000 women. It's crimes against humanity and all of the world's citizens have a responsibility to speak out against it."
"Fifteen-year-old young girls were subjected to torture and raped by countless men for weeks, months and years on end," she added.
The comfort women were forced into brothels for Japanese soldiers in the 1930s and during World War II.
Japan's failure to apologise and issue official compensation remains an irritant in relations with the nations affected.
In South Korea, surviving "comfort women" still demonstrate every Wednesday outside the Japanese embassy in Seoul. Many did not reveal their involvement for decades out of a sense of shame.
Japan set up a private compensation fund in 1995 as a way of offering recompense without officially acknowledging wrong.
But many women have rejected the offer, saying it should come from the government itself.