A report from The Inter-American Commission on Human Rights, an arm of the Organization of American States, says an inquiry or national action plan is needed to get at the root of the problem.
The report, issued in Washington, followed an investigation the commission conducted in Canada in 2013. The body spoke with government officials, opposition politicians and native representatives in both Ottawa and British Columbia.
"The IACHR considers that there is much more to understand and to acknowledge in relation to the missing and murdered indigenous women," the report said.
"This initiative must be organized in consultation with indigenous peoples, particularly indigenous women, at all stages."
The report said aboriginal women in Canada are murdered or disappear at a rate four times higher than their representation in the population.
Canadian activists who have been pressing a reluctant federal government for just such an inquiry welcomed the OAS report.
Claudette Dumont-Smith, executive director of the Native Women's Association of Canada, said the government should heed its warnings.
"This requires leadership from the government of Canada, since its leadership and participation is necessary in order to ensure nationwide co-ordinated, effective efforts," Dumont-Smith told a news conference in Ottawa.
"This is what the government has — so far — not done."
That sentiment was echoed by Holly Johnson, chair of the Canadian Feminist Alliance for International Action.
"Canadian governments have a lot of work to do to address the human rights abuses of aboriginal women, and this means addressing historic and current inequalities and discrimination that are at the root of this violence and the missing aboriginal women," Johnson said.
"The commission joins a growing demand across our country — and internationally now — for a national inquiry to understand how these factors affect women's vulnerability to violence and how these factors must be addressed."
Perry Bellegarde, national chief of the Assembly of First Nations, called the report valuable and insightful.
He said it identified "the critical failure of governments and policing across Canada to meet their obligations under international and regional human rights law to guarantee equality, by failing to exercise due diligence in preventing and responding to violence against indigenous women and girls."
Josh Paterson, executive director of the B.C. Civil Liberties Association, said governments are failing in their duty to prevent violence and discrimination.
"Governments must address the failure of the justice system and police to protect indigenous women and girls, but they must also do much more to ensure that indigenous women's fundamental human rights are protected," he said.
The 125-page commission report commended the federal government and provincial counterparts for their willingness to discuss the problem. But it noted the need for a broad and co-ordinated approach.
"The fact that indigenous women in Canada experience institutional and structural inequalities resulting from entrenched historical discrimination and inequality is acknowledged by the government of Canada and by civil society organizations," it said.
"There is also agreement on certain root causes of the high levels of violence against indigenous women and the existing vulnerabilities that make indigenous women more susceptible to violence."
Aboriginal women must participate in any programs, policies and initiatives aimed at the problem, it recommended.