The government said on Thursday two ferries collided on Lake Mai-Ndombe, which means "Black Water" and is about 400 km (250 miles) northwest of the capital Kinshasa.
Minister of Humanitarian Affairs Catherine Nzuzi wa Mbombo said 222 people escaped from the disaster. The two ferries were carrying an estimated 450-500 people. The accident occurred during a storm on Monday .
"It was two boats that collided due to a strong storm. The latest information we received at 8.30 a.m. this morning is that we're talking about 163 dead, that's bodies found," she said.
She said the search for survivors was continuing.
Lake Mai-Ndombe covers 2300 sq km but doubles or triples in size during the rainy season.
The western regions of the vast central African country have been deluged by heavy downpours as the rainy season gets into full swing.