The inquiry into the Bisesero massacre was closed in July, French media revealed this week.
Six survivors joined NGOs in 2005 in accusing the French army of knowingly leaving hundreds of members of the Tutsi minority to be slaughtered by militias linked to the Hutu-dominated government, which had previously enjoyed French support.
Despite promising to save them on the 27 June, the military failed to intervene until the 30, they claimed, leaving hundreds of Tutsis to their fate.
The campaigners intend to call for new angles to be pursued before investigating magistrates make a final decision on the case to "avoid a denial of justice".
"It's not right that high-ranking soldiers who were questioned contradicted each other on facts that are beyind question," Survie's Eric Plouvier told RFI. "It's not right that the judges refuse to confront them. So we're going to repeat our demands."
Chief-of-staff not questioned
They have criticised the inquiry's failure to question then defence minister François Léotard and former chief-of-staff Admiral Jacques Lanxade and his deputy General Raymond Germanos.
The Survie NGO claims the later pair were informed on 27 June that Tutsis had been attacked but did not issue orders to help them.
Lanxade has claimed that they only discovered what was going on gradually and insists that his conscience is clear.
Rwandan President Paul Kagame has accused the French of supporting the Hutu government and participating in the genocide, which cost about 800,000 lives.
France denies the accusations.