JOHANNESBURG, South Africa — Death rates in Congo remain far higher than elsewhere in Africa despite years of relative peace and elections that were designed to bring stability to the beleaguered nation, according to a report released yesterday by the International Rescue Committee.

Between January 2006 and April 2007, sporadic conflict and related effects such as closure of clinics and disruption of food supplies caused the deaths of approximately 727,000 people, the group estimated.

The report is the latest of several detailed surveys by the humanitarian aid group showing that since the outbreak of war in 1998, Congo has experienced one of the world’s deadliest crises. The group estimates that the conflict and its aftermath have led to the deaths of 5.4 million people, more than 8% of the country’s population of 66 million.

Instability in the central African nation continued to take a huge toll even as violent deaths declined after the war officially ended with a peace agreement in 2002. The biggest killers today are preventable or treatable maladies such as malaria, diarrhea, and respiratory illnesses, made far more serious by a shortage of medical care in the chaotic postwar environment.

The report says violent deaths amounted to only one out of every 250 fatalities in Congo in the survey period, between January 2006 and April 2007.

Teams of workers interviewed 14,000 randomly selected residents in dozens of separate zones about recent deaths in their homes. To reach one village selected randomly by a computer, one of the report’s authors, Richard Brennan, said, surveyors had to travel five hours by four-wheel-drive truck and an hour by boat before hiking for two more hours up a hillside.