LOS ANGELES — Federal authorities Thursday 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 after massive amounts of cash were seized in a raid.

The Treasury Department’s Financial Crimes Enforcement Network issued an order requiring the businesses to report any transaction involving more than $3,000. The geographic targeting order – a tool used to track and deter money laundering – is one of the largest issued to date, said Jennifer Shasky Calvery, the network’s director.

“We’re hoping this is going to disrupt the ability of some of the most prominent drug trafficking organizations out there to launder and use their money to continue their illegal activities,” she said. “Our goal here is to make it so they can’t move their funds.”

Authorities are serving 2,000 businesses with notice of the order, which will last six months, she said.

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.

During the raids, federal agents seized more than $90 million in cash and more than $30 million in bank accounts.