(Reuters) -Chaotic scenes unfolded in the eastern Congo city of Bukavu on Saturday after Rwanda-backed M23 rebels reached its outskirts, while a threat by Uganda's army chief to attack a Congolese town raised fears of the conflict flaring into a wider regional war.

The Rwandan-backed rebels' entry into Bukavu follows their capture of Goma, defying international calls for a ceasefire.

The DRC government has repeatedly accused Rwanda of supporting the M23 rebel group, a claim that Rwanda denies. Kigali, in turn, alleges that Kinshasa collaborates with the Democratic Forces for the Liberation of Rwanda (FDLR), a Hutu armed group with ties to the perpetrators of the 1994 Rwandan genocide, an allegation the DRC rejects.