The M23 militia consists of soldiers who rebelled this year, saying the government reneged on a peace agreement brokered in 2009. Its leader, Bosco Ntaganda, is suspected of conscripting child soldiers into the rebel group.
Recent fighting in North Kivu province in eastern DRC left more than 150 rebels and two government troops dead. Julien Paluku, North Kivu's governor, told the BBC he received a phone call from rebels in the eastern city of Goma saying they would "spend the night." The governor, however, said rebel elements would be overcome.
Governments from neighboring Uganda and Rwanda are accused of backing the M23 rebellion, an allegation they each deny. The British government had said it was reviewing its foreign aid to Rwanda given the allegations of M23 support.
The United Nations this week said it uncovered evidence that suggests at least 264 were arbitrarily executed by rebel forces in DRC this year.
Navi Pillay, U.N. high commissioner for human rights, said about 30 percent of those killed by militants in eastern DRC were children, which amounted to what she said were "systematic" human rights abuses.