Families of the disappeared from all eight districts of the Tamil homeland participated in a rally in Mannar on Wednesday.
Demonstrating outside the Mannar government agent office, the protesters demanded action to identify the victims found in the Mannar mass grave.
Latest reports tally the number of skeletons found at the Mannar mass grave to 276, with at least 21 children. As well as signs of torture, observers had been disturbed by the discovery of bones bound by metal.
The findings have raised fresh concerns over the fate of forcibly disappeared Tamils.