The motive for the attacks was not clear but militia violence in Congo is linked to long-running competition for influence and the region's rich mineral resources.
The Allied Democratic Forces (ADF), a rebel group, are alleged to have killed more than 40 people in an attack on Mayikengo village this week and over 80 in attacks on other villages in the province the previous week.
The incident was caused by night sailing, Rita Bola Dula, Mai-Ndombe province governor, told Reuters, adding that the investigations continued.
All 53 face charges including illegal arms possession, criminal conspiracy, terrorism and attempts to destabilise state institutions and undermine the integrity of the state.
US strongly condemned the attack that claimed nine lives on May 3 this year.
The head of the Lac Vert district where the incident occurred, Dedesi Mitima, told Reuters he had seen the bodies of seven children and two men at the camp.
The DRC demanded the withdrawal despite UN concerns about rampant violence in the east of the country.
The M23, a rebel group, has faced accusations from both the UN and international human rights organizations of perpetrating atrocities in eastern DRC.
The country currently has 6.7 million people displaced within its borders, amid serious flooding emergencies and a resurgence of measles and cholera outbreaks.
The United States-based Center for Civilians in Conflict on Tuesday denounced the use of heavy artillery and mortar shells against civilian installations.
The SADC regional force, deployed to eastern DR Congo in December 2023, comprises troops from South Africa, Malawi, and Tanzania.
The president of the Democratic Republic of Congo, Felix Tshisekedi, was to be sworn in for a second five-year term on Saturday after sweeping elections which the opposition has branded a sham, calling for protests.
Police in the Democratic Republic of Congo's capital Kinshasa prevented protesters from assembling Wednesday, AFP reporters saw, after a demonstration against recent elections was banned in the fragile central African state.
The East African Community (EAC) first deployed troops in the violence-plagued region in November last year after the resurgence of the M23 rebel group.
This week, the Independent National Electoral Commission (CENI) officially announced that it had registered 26 Presidential candidates, among them President Félix Tshisekedi, who seeks a second term.
Hundreds of thousands of people are crammed into miserable displacement camps around the city, hastily erected on fields of mud.