The boat - a narrow, double-ended open vessel - caught fire on the Congo River near Malange village in Lukolela territory on Thursday evening, leaving 146 people missing, the Ministry of Social Affairs said in the memo.
Rescue teams recovered 209 survivors, several with injuries, after the vessel burned and drifted downstream, the note said.
The fire also destroyed cargo on board and ignited 15 riverside homes.
Search operations continued on Friday with naval personnel and community volunteers combing the banks while authorities pledged medical care for the injured, assistance to bereaved families and the repatriation of survivors to their places of origin and destination.
River transport is a lifeline in DR Congo's vast rainforest regions, where old wooden vessels are the main form of transport between villages but accidents are frequent due to overloading, poor maintenance and the use of riverboats at night.
The accident comes days after at least 86 people died in a separate shipwreck on Wednesday night at the confluence of the Nsolo and Great Maringa rivers in Basankusu territory after a river boat sank on Wednesday, state media reported on Thursday adding that local residents pulled eight survivors from the water.
"The motorised canoe … sank due to blatant overloading and nighttime navigation, which is formally prohibited," civil society activist Akula Mboyo said in a statement.
Rescue operations are often hampered by limited resources and the remote locations of accident.
Reuters could not independently verify the death toll in Basankusu and officials were not immediately reachable for comment.
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