Online wine sales accounted for a mere five percent of global sales of whites and reds and roses last year but are expected to rise sharply, according to a study released Monday at France's Vinexpo wine fair.

Cellars and stores still account for the vast majority of wine purchases worldwide but online sales, amounting to $6 billion (5.3 billion euros), have become a crucial channel for sales with an around sixfold increase since 2006, said Bordeaux's Kedge Business School.

There were vast differences worldwide, the study said, saying online wine sales accounted for four percent of the wine market in the United States, the globe's top market in value and volume, nine percent in France, 11 percent in Britain and 20 percent of wine imports in China.

In the same countries, the number of wine buyers online was lowest at 23 percent in the United States, at 25 percent in France, 26 percent in Britain and more than 30 percent in China.

Researcher Gregory Bressolles who headed the study said 2015 will be a turning point as "the online market will no longer be driven by wine-cellars. It will no longer depend on them," he said. "It now depends on buyers."

The study said amazon.com was the top website for wine buying, followed by China's jiuxan.com and spain's laviania.es and France's lavinia.fr.