Federal authorities have slapped new financial reporting rules on 2,000 businesses in the fashion district of Los Angeles in an effort to curtail suspected Mexican drug money laundering.

The Treasury Department's Financial Crimes Enforcement Network issued an order Thursday requiring the businesses to report to authorities any transaction involving more than $3,000. The order will last six months.

Network director Jennifer Shasky Calvery says it is one of the biggest geographic targeting orders — a tool used to track and deter money laundering — issued to date.

The move comes after federal authorities raided dozens of businesses in the Los Angeles fashion district last month and arrested nine people in cases involving accusations of money laundering through international trade.

Companies typically are required to report cash transactions bigger than $10,000.