Buyers who use shell companies to pay cash for $1 million or more homes will have their identities reported to federal authorities.

Federal authorities on Wednesday announced a temporary, anti-money-laundering crackdown on pricey homes bought secretly with cash in Miami-Dade County and New York City.

The new policy will require title insurance companies to identify the true owners of shell companies that pay $1 million or more in cash for homes in Miami-Dade and $3 million or more for homes in New York City. Insurers will then have to report the names of the buyers to the U.S. Treasury Department.

The move reflects concerns that dirty money from abroad is helping fuel the local residential real estate boom. Wealthy buyers in South Florida often use a network of domestic and offshore companies to prevent their names becoming public. Using a limited liability company to buy property also offers owners legal benefits such as liability protection and tax breaks.