Bujumbura - Soldiers opened fire on Hutu civilians who had been forcibly moved to a camp outside the capital, killing 13, one of the survivors said on Saturday.
But the army said six were killed and seven injured.
A woman, who did not want to be further identified, said on Friday soldiers came to Ruyaga camp 13 kilometres east of Bujumbura and asked where Hutu rebels were hiding.
"We said we did not know, and they began shooting at us," she said.
The Tutsi-dominated government of President Pierre Buyoya has said Hutu civilians have been moved from their homes in the capital to temporary camps outside for their own protection since Hutu rebels stepped up attacks on the capital in the past six weeks. Several dozen people, including civilians, soldiers and rebels, have been killed.
United Nations agencies and other relief organizations estimate that at least 250 000 people have been moved to the camps. Ruyaga houses some 30 000 people in precarious conditions.
Army spokesperson Colonel Longin Minani said on Saturday that one soldier had killed six people and wounded seven others.
"One soldier left his position without any mission and went to Ruyaga protected site around 5:30pm (1530 GMT). He asked one suspicious person for his identity card, and that person ran away," Minani told reporters.
"The undisciplined soldier opened fire, and the bullets hit people who were running in all directions because of panic."
Minani said military police had gone to the camp in search of the soldier who would be tried by a court martial.
Both the European Union and the United States have criticized the forced move of civilians to the camps, and the UN World Food Programme says it is distributing food on a "need only" basis.
A vicious cycle of violence erupted in Burundi in October 1993 after Tutsi paratroopers assassinated the country's first democratically elected president, a Hutu. Tutsis had been in control of the tiny central African nation since independence from Belgium in 1962.
Hutus vented their rage on minority Tutsis, then the Tutsi-dominated army and Tutsi militia lashed out at Hutus.
Since then, more than 200 000 people, most of them civilians, have been killed in the violence.
Hutus make up a majority in Burundi's population of 6,5
million. - Sapa-AP