In a resolution passed today, the NPC questioned the legal possibilities of conducting a credible domestic investigation in preference to an international mechanism.
"...The Council calls upon the international community to set up an international tribunal to try those alleged to have committed international crimes against the Tamil People in Sri Lanka," the resolution titled 'The Need for an International Mechanism' said.
The resolution also noted that the victims of the 26-year war, which ended in 2009, were spread across many countries.
CV Wigneswaran, Chief Minister of the province, has also demanded a credible international investigation mechanism. The council awaits the release of the OHCHR Investigation on Sri Lanka (OISL) report.
The NPC resolution has come a week after the US said it would back a domestic inquiry. The announcement by the US signals a reversal in its longstanding insistence on an international inquiry.
Former president Mahinda Rajapaksa resisted international pressure to investigate war crimes allegations during his tenure, straining the US-Lanka ties.
Rajapksa had claimed that any international investigation would be an attack on the island's sovereignty.
In January, he suffered a surprise defeat from Maithripala Sirisena, who had in the run up to the election pledged a domestic mechanism to an international one.
Last week, Prime Minister Ranil Wickremesinghe claimed that there was no legal basis for an international probe.
