The ACF in a statement accused the Sri Lankan authorities of lacking the will to find those responsible for the deaths in the northeastern town of Muttur in August 2006.
"One cannot but notice that these procedures have failed, and that the Sri Lankan government obviously lacks will to establish the truth," the statement said.
"Action Against Hunger reiterates its call, notably to the European Union, to constitute an internationalised inquiry into this massacre."
The statement came after a Sri Lankan investigation cleared the military of killing the 17 employees of the charity and ordered more compensation for the families of the victims.
The Commission of Inquiry in its final report to President Mahinda Rajapakse said neither the army nor the navy was present in the area as alleged when the massacre took place, two privately-run newspapers said this week.
Thirteen men and four women who worked on water sanitation and farm projects for ACF were found shot dead in an area whe