Democratic Republic of Congo's government and Rwandan-backed M23 rebels traded blame on Friday for explosions at a rally in the rebel-held eastern city of Bukavu that killed 13 people and wounded scores.
The finger-pointing over Thursday's incident has further inflamed tensions in eastern Congo, where a rebel advance this year has drawn in neighboring armies, raising fears of a regional war.
Congo's army said Rwandan troops and rebels fired rockets and grenades into a crowd gathered on Thursday in Bukavu's central square for a speech by one of M23's leaders.
"The Rwandan army and its (proxies) bombed and fired live ammunition at the civilian population," Congo's interior ministry said in a statement posted on X.
A Rwandan government spokesperson did not immediately respond to a request for comment. Kigali denies supporting M23.
Corneille Nangaa, leader of a rebel alliance that includes M23, blamed Congo's president, Felix Tshisekedi. Nangaa said on Thursday the grenades were the same type used by Burundi's army, which is supporting Congolese forces.
Reuters could not independently verify this. Burundi's army spokesman said none of its soldiers were in Bukavu, without addressing the grenade allegation.
Two witnesses told Reuters they saw an attacker try to fire a grenade at a convoy of rebel leaders but miss his target, instead killing people gathered at the rally.
"The grenade exploded too soon," one of the witnesses said. Both said the blast killed the attacker.
Bukavu residents volunteered on Friday to donate blood for the wounded after hearing blood stocks were depleted.
A medical source said on Thursday the city's general hospital was treating 68 people for injuries. Congo's interior ministry said "nearly 100" had been seriously wounded.