DAKAR (Reuters) - Ethnic violence in northwestern Democratic Republic of Congo killed at least 400 people over two days in December, a local priest and a civil society activist said on Monday, a death toll three times higher than earlier estimates.

The clashes on Dec. 16-17 between the Batende and Banunu ethnic groups in and around the town of Yumbi were some of the worst to hit the normally peaceful area in years, and led the government to cancel voting in the Dec. 30 presidential election there.