Some of the Tamil guerrilla leaders linked to atrocities have defected to the government since the conflict ended, and there have been allegations that the authorities were trying to protect them.
Sri Lanka's 37-year ethnic war, which ended in 2009, mainly pitted the majority ethnic Sinhalese, who are Buddhists, against the minority Tamils, who are mainly Hindus and live in the north.
Muslims, who account for around 10 percent of the population, largely avoided taking sides in the fighting.
But there have been allegations that the Tamil Tiger rebels carried out several massacres of Muslims in the east as part of their push to create a separate Tamil homeland.
The site in the eastern coastal town of Kalavanchikudy has been under investigation since a resident petitioned the local court, claiming the remains of around 100 Muslims killed 24 years ago at the height of Sri Lanka's ethnic war were buried there.
The claims of a mass grave in the east of the island follow the discovery of s