A resident of nearby Saint-Andre de Cubzac found the body, sources in the investigation told AFP on condition of anonymity, but the body was not yet confirmed as Lam Kok's.
"The site of the discovery is located between the site of the crash and the place where the bodies of two other passengers were found," an official said.
"But we have to wait for DNA matches as part of the forensic investigation," the official added.
The 46-year-old tea magnate had invited the press to his lush new property on December 20 to celebrate his $41-million purchase.
He took off on a helicopter tour of the estate — which he intended to turn into an elite tea- and wine-tasting retreat — with his 12-year-old son, his financial adviser and the chateau's former owner. The three other bodies have been found but the tycoon was still missing.
James Gregoire, who died in the crash on the day he handed over the property to Lam Kok, had bought the chateau in 2003 after the previous chateau owner died in a plane crash.
Wealthy Chinese have developed a taste for fine French wines, and their buying power has been credited with pushing prices for certain vintages to record levels. In recent years they have increasingly taken to buying French vineyards as well.