The powerful federal government's Black Economy Taskforce is investigating allegations that foreign exporters, often on tourist visas, are smuggling "suitcases of money" into the country to buy crops that are still in the ground, or on the vine.

Victorian and South Australian farmers claim they are being paid up to $56,000 in bundles of $50 and $100 notes by Chinese exporters for filling shipping containers with cartons of grapes that are directly shipped to mainland China.