At a ceremony marking the 14th anniversary of the mass slaughter in Rwanda, U.N. Secretary-General Ban Ki-moon pledged to step up efforts to prevent another genocide.

Hanging over the commemoration at United Nations headquarters in New York on Monday was the 5-year conflict in Darfur, which the world body says has left more than 200,000 people dead and forced at least 2.5 million to flee their homes.

Eugenie Mukeshimana, who lost her husband and parents in the Rwanda genocide, told several hundred staffers that the sense of loss that survivors feel is deep. She said some mothers in Rwanda have no children, no home, no food and no medical care.

“They are still hoping that the future will be better not only for them but for future generations,” she said. “However, we are also concerned that what happened to us is happening now to mothers in Darfur, and it could be happening in the future if we don’t pay attention.”

Mukeshimana, who was pregnant during the genocide and now has a 14-year-old daughter, then lit a candle in memory of the victims, surrounded by nine Rwandan children.

Rwanda’s genocide began hours after a plane carrying President Juvenal Habyarimana was mysteriously shot down as it approached the capital, Kigali, on April 6, 1994.

The 100-day slaughter, in which more than 500,000 minority Tutsis and moderate members of the Hutu majority were killed by Hutu extremists, ended after rebels ousted the Hutu government that orchestrated the killings.

The secretary-general stressed that the U.N. _ which did nothing to stop the genocide _ “has a moral duty to act on the lessons of Rwanda.”

“That is why this day is also a call to bolster efforts to prevent another genocide,” he said. “It is a cause I am resolved to pursue, in my time as U.N. secretary-general and in the years beyond.”

Ban said he has appointed special advisers to prevent genocide and to protect civilians facing possible war crimes, crimes against humanity or genocide. “I will spare no effort in working with member states to translate this principle from word to deed,” he said.

Rwanda’s U.N. Ambassador Joseph Nsengimana urged the United Nations to reject attempts at “revisionism,” which would deny the genocide.