The Democratic Republic of Congo has accused Rwanda of killing more than 1,500 civilians in eastern Congo since early December, when the M23 rebel group, backed by the Kigali government, launched a new offensive.

The Congolese government said in a statement that the death toll was based on information from civil society and confirmed by humanitarian organizations and government agencies.

Congolese authorities have described the new wave of violence as a clear violation of the country's sovereignty and a serious and repeated violation of international law.

M23 rebels seized the key town of Uvira in South Kivu early last month, prompting tens of thousands of people to flee across the border into Burundi.

The M23 launched this new offensive just days after the Congolese and Rwandan governments signed a US-brokered peace agreement on December 4.

According to the United Nations, nearly 500,000 people have been displaced by the recent fighting in South Kivu.