Management from four Polish sugar holding companies have formed an informal cartel, effectively stopping production of 70% of the domestic market in a bid to drive up sugar prices, according to unconfirmed industry sources. It is believed that the company leaders met last week in Warsaw, at the invitation of deputy agriculture minister Feliks Klimczak. There, they allegedly agreed to put a hold on production until a minimum wholesale price of PlZZ2.10 per kg could be guaranteed.