The 1892 oil painting "Nafea faa ipoipo?" (When Will You Marry?) was created during a visit by the French post-impressionist master to Tahiti and is considered one of his major works.
"I know how much it is, but I cannot talk about it," said Ruedi Staechelin, grandson to the namesake of the Basel-based Rudolf Staechelin Family Trust, which sold the painting.
Staechelin cited a confidentiality clause in the sale agreement when pressed for details on the amount and identity of the buyer, rumoured to be from the oil-rich nation of Qatar.
The New York Times, citing art world insiders, put the sale price at close to $300 million, which would make it one of the most expensive paintings ever sold.
"I've heard a lot of numbers but they are wrong," Staechelin said, refusing to elaborate."
It was part of a collection of impressionist and post-impressionist works amassed by Rudolf Staechelin, an entrepreneur.
"It's a piece that my grandfather bought and which has been in the family for many years," said Ruedi Staechelin, adding that the family wants to diversify its assets rather than concentrate on art.
The work, which has been on loan to the Kunstmuseum Basel for nearly half a century, will go on display Sunday at the Beyeler Foundation near the city of Basel.
"It's a very harmonious piece, well carried out and possessing an extraordinary beauty," said exhibition curator Martin Schwander.