Congolese authorities have failed to prevent widespread rapes, Human Rights Watch said in a new report, citing U.N. data showing 7,703 cases of sexual violence by the army were reported last year.
Most victims were adolescent girls.
While soldiers now face legal action for rape, senior officers "continue to be untouched," said Juliane Kippenberg, Africa researcher for the group.
"Their own crimes and their command responsibility for the crimes of their soldiers must be investigated and held to account," she said.
Tens of thousands of women and girls in Congo have suffered from abuse, including gang rape and other violent sexual acts that have led to unwanted pregnancies, serious injuries and death.
In its report, Human Rights Watch called on the U.N.'s Security Council to take "tough measures," including travel bans, and other sanctions against individuals or governments that commit or condone sexual violence in Congo and elsewhere.
It urged Congo's President Joseph Kabila to set up special tribunals that include international judges and prosecutors to target sexual violence in the army. The military justice system is weak, it said, and only a small number of acts of sexual abuse by lower rank soldiers have been prosecuted.
Both the U.N.'s Congo peacekeeping mission and EU projects to reform and train Congo's military must put more emphasis on teaching soldiers international humanitarian law and on improving the command structure, Kippenberg said.
"Reforms so far have achieved shockingly little in reducing sexual violence against women and girls," she said.
Congo has been wracked by conflict since genocidal forces from Rwanda fled into its forested mountains 15 years ago.
The conflict in eastern Congo at its height drew in half a dozen of the country's neighbors, each greedy for a share of the region's rich mineral resources.
More than five million have been killed and hundreds of thousands left homeless over the past decade, with brutalities commonplace in rural communities.
A 2003 peace deal reduced the fighting but both the army and rebel groups continue to attack villages and kill civilians.
By Associated Press Writer Constant Brand