BAGHDAD — Iraq is investigating the circumstances surrounding years-old unidentified human remains that were buried recently in Karbala province. Sunni groups allege the Iraqi government tried to hide evidence of sectarian violence by disposing of the bodies in unmarked graves — a charge the government denies.

The 31 bodies had been held for at least two years in the Babylon province Health Directorate morgue before being turned over earlier this month to a charity for burial in a cemetery in neighboring Karbala province.

A video posted Aug. 10 on social media showed people from the Fatima Zahra Foundation burying the bodies. That alone raises sectarian controversy, as the charity is affiliated with the Popular Mobilization Units (PMU). The PMU is predominately Shiite, and many of its factions are backed by Iran. Critics believe the bodies belonged to displaced Sunnis from northwestern Iraq.

Sunni parties issued several statements holding government agencies responsible for the displacement and killing of Sunni families from the area of Jurf al-Sakhar, northern Babylon.