Analysts say the deadly march by Rwanda-backed rebels across eastern Congo could widen into a regional conflict drawing in even more countries, and two neighboring nations with the most involvement in the mineral-rich area might be the key to stopping the violence.

U.N. human rights chief Volker Turk said on Friday that the worst could be ahead in the escalating crisis in eastern Congo, saying he expected sexual violence including incidents of rape and sexual slavery to increase.

Worse violence "may be yet to come" in the conflict-hit Democratic Republic of Congo, UN High Commissioner for Human Rights Volker Türk said on Friday. An offensive by the Rwanda-backed M23 rebel group against Congolese forces in and around the eastern city of Goma has left almost 3,