Rwanda's ally Uganda, unhappy about another rebel group in DR Congo that threatens its security, has also been accused of helping the M23 - with its officers also spotted at Tchanzu. The UN experts say Uganda has also supplied weapons, hosted rebel leaders and allowed cross-border movements of M23 fighters - accusations Kampala denies.

In the capital, Kinshasa, protesters complaining of a lack of international action attacked foreign embassies, including those of the U.S., France and Rwanda.

Many Congolese see the rebel advance as an invasion of their country by a foreign power in an attempt to seize land and Congo’s valuable rare minerals.