Cedric Mandembo, who competed in the +100kg category, boxing coach Blaise Bekwa, athletics coach Guy Nkita and judo coach Ibula Masengo have not been seen since the Games came to a close on Sunday evening, the source said, requesting anonymity.
The country's 12-strong delegation to the Games is due back in Kinshasa on Thursday.
An informed source in the capital said national boxing coach Bekwa disappeared from the Athletes' Village on Friday while Nkita, national athletics technical director, had left the area just after Ilunga Mande pulled out of the men's marathon. Masengo was reported to have disappeared Saturday night while Mandembo was said to have disappeared just after the closing ceremony on Sunday evening.
Asked about the disappearances, the minister of sport and youth, Baudoin Banza Mukalay, said: "I don't know... I left London this morning. Yesterday (Sunday) I was with officials before the closing ceremony.
"They gave me a report that everything was going well."
According to Mukalay, the Congolese delegation is due back in Kinshasa before Wednesday.
The country's four athletes did not shine at the Games: Mandembo lost his first fight after only 49 seconds; Ilunga Sankuru finished 14th out of 15 in the women's 1500m; while boxer Mwamba Meji lost on a referee's decision.
Marathon runner Ilunga Mande pulled out two kilometres from the finish.
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