It’s time to set up a commission of inquiry. Asean cannot stand by.

Today European foreign ministers are meeting in Brussels to discuss, among other issues, a resolution on Burma to be tabled at the United Nations General Assembly. Later this month, members of parliament from Southeast Asia will gather for the Asean Inter-Parliamentary Association meeting in Phnom Penh, Cambodia. Both are opportunities to build momentum for a United Nations-led commission of inquiry into possible crimes against humanity and war crimes in Burma.

To date, 16 countries, including the United States, Canada, the United Kingdom, Australia and the Czech Republic, have called for a commission. Yet Burma’s Asean neighbors have remained silent. Perhaps some consider such a move gratuitous and meddlesome. But if Asean is to assert itself as a leading organization on the global stage, its members need to send a clear message that crimes against humanity affect the entire region and will not be tolerated.

An inquiry would not be a political tool for assigning criminal liability; rather, it would be a mechanism to document atrocities committed in Burma over the years and help prevent future atrocities by encouraging policy reforms in Burma’s judicial system. It would also provide victims of Burma’s protracted civil war an opportunity to seek justice for their grievances, and so contribute to building a lasting peace.

Human rights monitors have documented abuses in Burma for more than two decades, and the U.N. General Assembly has passed 20 resolutions describing possible crimes. In March 2010, Tomás Ojea Quintana, the U.N.’s Special Rapporteur on the Situation of Human Rights in Myanmar, recommended establishing a commission of inquiry. Leaving Burma after a five-day mission last week, Mr. Quintana reiterated his position.

An international investigation is urgently needed because the Burmese government has failed to respond to appeals from its people. In 2007, deep-seated discontent spurred tens of thousands of Buddhist monks to take to the streets to demand change. Instead of engaging the monks in constructive discussions, the military junta opened fire on the religious leaders. Today more than 2,000 prisoners of conscience remain in prison.

The Burmese government is trying to head off pressure for a commission of inquiry by raising hopes it will now pursue reforms. In 2008 it held a referendum on a new constitution to restore civilian rule. However, this constitution is severely flawed, since it protects those who committed abuses in the past.

The Association of Southeast Asian Nations has nevertheless hailed the new government as a step forward, calling on the European Union and the United States to lift sanctions. However, Asean states did not consider the ramifications the elections would have on Burma’s armed conflict. In the aftermath of the elections a number of ceasefire agreements between the government and non-state armed groups broke down.

In June 2011 renewed hostilities between government forces and the Kachin Independence Army led to widespread abuses against civilians in Kachin State provoking over 20,000 people to flee their homes. Thousands of refugees spilled across the borders to Thailand and China. Asean was slow to respond and has yet to develop a mechanism to protect refugees and ensure civilians protection from human rights abuses.

In contested areas of Shan State, where government troops continue to battle ethnic Shan armed groups, there have been credible reports of systematic rape. In a statement released on July 22, Eva Kusuma Sundari, a member of the Indonesian Parliament and President of the Asean Inter-Parliamentary Myanmar Caucus declared “We [AIPMC] call on the Myanmar Army to immediately end rights abuses, particularly the systematic use of rape as a weapon to suppress ethnic women and to urgently engage in peace talks with ethnic armed groups.”

Burmese President Thein Sein recently made overtures to the political opposition, meeting with Aung San Suu Kyi and offering peace talks with some of the armed groups. Genuine multiparty dialogue is welcome, but progress toward political reconciliation is not a substitute for seeking truth and justice. An independent U.N.-led investigation that examines reports of human rights violations committed by both the government and non-state actors would complement talks.

President Thein Sein also recently announced that Burma is ready and committed to take a stronger leadership role in the region. On Aug. 21, he declared in Parliament that his government intends to assume the Asean chairmanship in 2014. The government should demonstrate its readiness to chair the regional body in action as well as words. Cooperating with a potential international investigation would be a step in the right direction.

All those who care about the rights and dignity of the citizens of Burma should support the call for a commission of inquiry. Without accountability, allegations of grave human rights violations will continue to poison the development of Burma and Asean.

Mr. Tanada is a member of the Philippines Congress and the vice president of the Asean Inter-Parliamentary Myanmar Caucus.