In 2012, when M23 rebels appeared poised to seize control of a major city in eastern Congo, western countries suspended aid to put pressure on Rwanda to withdraw its support.
A Rwanda-backed militia seized the pivotal Congolese city of Goma this week, threatening a new humanitarian crisis after decades of fighting.
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.
After a lightning offensive, M23 rebels now control Goma, a large city in the eastern Democratic Republic of Congo.
The United Nations expressed deep concern at reports of M23 rebels and Rwandan troops advancing south towards the Congolese city of Bukavu on Thursday, as the militants sought also to assert their control over east Congo's largest city Goma.
U.S. Secretary of State Marco Rubio called for a urgent cease-fire in the conflict in eastern Democratic Republic of Congo saying Washington was "deeply troubled" by a recent escalation in the fighting.
Rebels claim to have captured the key city of Goma in the DRC, as the decades-long conflict becomes even more volatile. Sky News takes a look at what's going on.
GOMA, Democratic Republic of Congo - Rwandan President Paul Kagame blasted criticism of his country's role in eastern Democratic Republic of Congo where rebels his government backs have seized its largest city,
Congo's security forces are fighting against Rwanda-backed rebels who advanced into a key eastern city in a major escalation of a decadeslong conflict.
The M23 militia, funded and directed by Rwanda, said it had seized the city of Goma, terrifying its people, many of whom sought shelter there after fleeing the rebel advance.
France expresses its solidarity regarding the Democratic Republic of Congo and condemns actions by Rwanda in the country, French Foreign Minister Jean-Noel Barrot said on Monday.