Sydney | China has given Australia's top wine exporters until Friday to answer preliminary questions related to its anti-dumping investigation in a move some investors fear will enable Beijing to slap tariffs on $1.2 billion of exports within months.

China's Ministry of Commerce wrote to 31 major winemakers, including Treasury Wine Estates and Accolade Wines, on September 15 to issue them with an "interim sampling" questionnaire about their operations. They were given 10 days to respond.