Four people were feared dead Saturday including a Chinese billionaire and his 12-year-old son after the helicopter in which he was overflying his newly purchased French vineyard crashed into a river.

Lam Kok, the 46-year-old head of the Hong Kong-based Brilliant group, had just bought a major Bordeaux vineyard in a sale accompanied by great fanfare and was surveying his new property in a helicopter piloted by the former owner when the accident happened Friday.

Emergency workers pulled a still-unidentified body from inside the helicopter after finding the wreckage in the Dordogne river, said local officials.

A large search operation was called off just before midnight with the helicopter's other three occupants still missing. Officials said the search would resume Saturday morning.

The helicopter was flown by James Gregoire, the former owner of the Chateau de la Riviere vineyard, and was carrying the Chinese billionaire, his son and an interpreter.

Lam Kok's wife pulled out of the aerial tour at the last minute, saying she was "scared of helicopters", said an AFP photographer at the event. Gregoire meanwhile patiently carried out his pre-flight procedures, a check-list resting on his knees, the photographer said.

The accident happened at the end of a festive day marking Thursday's sale of the Chateau de la Riviere, one of the region's oldest estates.

After a press conference, an introduction to the staff and dinner, the former owner was planning to take his buyer on a short tour of the 65-hectare (160-acre) vineyards and surrounding grounds.

When they did not return after 20 minutes, employees at the vineyard contacted emergency services.

A major search operation was launched using emergency helicopters, inflatable boats, rescue divers and around 100 officers on foot. Emergency workers managed to locate the wreckage in the river after police received a call from a witness who had seen the helicopter go down.

In a bizarre twist of fate, a previous owner of the Chateau de la Riviere was killed in a plane crash in 2002.

Gregoire bought the property, the largest in Bordeaux's Fronsac wine-producing region, the following year.

Earlier Friday, the vineyard's managing director, Xavier Buffo, said during a press conference the sale marked the largest Chinese investment in Bordeaux property to date.

Hong Kong-based Brilliant, which specialises in rare teas and luxury hotels in China, had said it wanted to turn the chateau into a high class tea and wine tasting centre.

The group -- whose interests range from Pu'er, a dark fermented tea from China's Yunnan region, to top-end resorts -- also planned to build a hotel near the vineyard.

Wealthy Chinese have developed a taste for the finest French wines and their extensive buying power has been credited with pushing prices for certain vintages to record levels.

In recent years they have increasingly taken to buying vineyards as well. But the value of each transaction has generally been under 10 million euros ($13.6 million).