GOMA, DEMOCRATIC REPUBLIC OF CONGO - At least 40 people have been killed in the last 48 hours in ethnic violence in northeastern Democratic Republic of Congo between Hema cattle herders and Lendu farmers, a local official said on Tuesday.

Fighting between the two groups instigated by Lendu-dominated militia has killed dozens since December.

Tensions between Hema and Lendu had mostly laid dormant since a 1999-2007 conflict in which tens of thousands of people died.

Local officials and activists have struggled to explain the latest outbreak of violence, but it appears to be motivated by competition over land and an absence of local authorities capable of arbitrating the dispute.

Civil society leader Jean Bosco Lalu told Reuters that the violence of the past two days appeared to consist of reprisals for earlier killings. A similar number of people died in the latest major clashes two weeks ago.

Violence across Congo has intensified since late 2016, when President Joseph Kabila refused to step down at the end of his constitutional mandate, undermining the legitimacy of the state.