The U.N. human rights chief said on Friday that he was deeply disturbed by the escalating crisis in eastern Congo, urging all those with influence to help halt the violence and warning of a risk that it spreads beyond the country's borders.

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,