KINSHASA (Reuters) - An ethnic Nande militia in eastern Democratic Republic of Congo killed about 30 civilians, mostly Hutus, on Sunday morning, local sources said, in an apparent escalation of deadly violence between the two groups that has flared repeatedly this year.

Joy Bokele, territorial administrator in North Kivu province’s Lubero territory, told Reuters that fighters from the Mai Mai Mazembe militia attacked the village of Luhanga at about 5 a.m. (0300 GMT) with guns and machetes.

Ethnic rivalries, incursions and competition for mineral-rich land have stoked conflict for two decades among eastern Congo’s dozens of armed groups, including many “Mai Mai” - self-defense militias originally created to resist Rwandan invasions.

The Mai Mai groups take their name from the word for “water” in a local Swahili dialect, because some of their fighters believe magic can turn flying bullets into water.

“For the time being, we have a provisional toll of about 30 deaths and about 20 wounded,” Bokele said.

Militias claiming to represent the two ethnic groups have engaged in tit-for-tat violence throughout the year that has killed dozens of civilians.

International powers fear tensions over President Joseph Kabila’s plan to stay in power beyond the end of his mandate next month could spark large-scale conflict that would feed into such local disputes. A 1998-2003 war in eastern Congo killed millions, mostly from hunger and disease.

Bokele said there was no known motive behind the attack but the Centre of Study for the Promotion of Peace, Democracy and Human Rights, a local activist group, said the killings followed a week of threats by the militiamen against local Hutus.

Tensions between the Hutu and neighboring communities have spiked since Congo’s army launched a military offensive last year against the main Hutu militia in the region, displacing large numbers of fighters and civilians.