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.

Rwandan-backed rebels have entered Bukavu, a major city in the mineral-rich east of the Democratic Republic of Congo.

Bukavu's fall, if confirmed, marks the armed group's most significant advance since it revived a decade-old insurgency in east Congo in 2022.