LOS ANGELES — Federal prosecutors on Tuesday expanded their crackdown on California medical marijuana dispensaries, filing three lawsuits and sending warning letters to more than 60 clinics in two Orange County cities.

The asset-forfeiture lawsuits filed against landlords who own buildings that house six marijuana shops in Anaheim and the letters order the closure of the clinics or possible criminal charges will be filed.

More than 300 pot stores and grows have been targeted in the Central District of California, which stretches from Santa Barbara to San Bernardino counties, since October when the state's four U.S. attorneys announced an effort to curb dispensaries.

Prosecutors argue dealers and suppliers are using the state's medical pot law, approved in 1996, as legal cover for running sophisticated drug-trafficking ventures in plain sight. Marijuana remains illegal under federal law.

Medical marijuana advocates argue the collectives are protected by California law, which allows the drug to be cultivated and supplied to ill people on a nonprofit basis.

The crackdown comes amid a shift by municipalities and law enforcement agencies that say the clinics are abusing the law and in some cases overrunning neighborhoods. Last month, the Los Angeles City Council voted to ban as many as 900 storefront dispensaries in the coming weeks.

A medical marijuana trade group has since sued the city, claiming the ban violated constitutional rights. Activists are also working to qualify a ballot measure to repeal the ban.

In all, 66 warning letters were sent to marijuana dispensaries in Anaheim and La Habra. Some have closed recently, but federal authorities said 38 remain open.

Related on HuffPost:

Dan Mick, spokesperson for the City of West Hollywood, confirmed to HuffPost that the following first four locations will remain open. The fifth store, Sunset Super Shop, is currently in dispute with the City so its future is unknown.
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  • The Farmacy

    8208 Santa Monica Blvd., West Hollywood, CA. (323) 848-7981.

  • Alternative Herbal Health Services

    7828 Santa Monica Blvd., West Hollywood, CA. (323) 654-8792.

  • Zen Healing

    8464 Santa Monica Blvd., West Hollywood, CA. (323) 656-6611.

  • Los Angeles Patients & Caregivers Group

    7213 Santa Monica Blvd., West Hollywood, CA. (323) 882-6033.

  • Sunset Super Shop

    This store is currently in dispute with the City of West Hollywood so its future is unknown, according to Dan Mick, spokesperson for the City. 8921 W. Sunset Boulevard West Hollywood, CA 90069 (310) 728-6200 Photo credit: <a href="http://www.facebook.com/pages/The-Sunset-Super-Shop/456204655214" target="_hplink">Facebook/Sunset Super Shop</a>