The United Nations secretary general, Ban Ki-moon, arrived in the Central African Republic on Saturday in an effort to drum up world support for an effort to stanch the widening sectarian conflict there.

He made the stop en route to Rwanda, where he was to commemorate the 20th anniversary of that country’s genocide.

“The international community failed the people of Rwanda 20 years ago,” he said in a speech to the interim Parliament. “And we are at risk of not doing enough for the people of the C.A.R. today.”

The Central African Republic has been roiled by a political conflict that turned into a communal clash between Christian and Muslim militias. Nearly 640,000 people have fled their homes. More than 80,000 people, mostly Muslims, have fled to neighboring countries. The country faces the risk of a de facto partition, with Muslim Seleka fighters in control of the east, and Christians concentrated in the west.