The aircraft plummeted to the ground when the animal, which had been smuggled into the cabin, sparked panic among passengers, the unnamed sole survivor told African magazine Jeune Afrique.
A British expert, who is investigating the crash for the Department for Transport, said he could not rule out a crocodile as the cause, but added it would be "extremely unlikely".
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
First Officer Chris Wilson, from Gloucestershire, was among those killed when the Let-410 plane crashed on August 25.
It was travelling from Kinshasa to Bandundu when the plane went down not far from its destination in an area of straw-covered huts.
According to reports, the accident followed a stampede of terrified passengers fleeing the crocodile after it freed itself from a sports bag in which it had been carried on board.
Tim Atkinson, of the Air Accidents Investigations Branch of the Department for Transport, dealing with the accident from the UK, said: "If this were the cause of the accident it is truly extraordinary.
"I would say it's extremely unlikely this story holds water but I wouldn't rule it out completely."
He added that there had been reports of passengers making their way to the front of the aircraft prior to landing, which may have led to the crash.
