Feds to announce Calif. pot dispensary crackdown

By LISA LEFF | October 7, 2011 | 3:45 AM EDT

FILE - In this Tuesday Jan. 26, 2010 file photo, a pedestrian walks past a marijuana leaf neon sign advertising a medical marijuana provider along a street in the Sherman Oaks section of Los Angeles, Calif. Federal prosecutors have launched a crackdown on pot dispensaries in California, warning the stores that they must shut down in 45 days or face criminal charges and confiscation of their property even if they are operating legally under the state’s 15-year-old medical marijuana law. (AP Photo/Richard Vogel)

SAN FRANCISCO (AP) — Federal prosecutors in California are announcing a coordinated crackdown on many of the state's medical marijuana dispensaries Friday.

The move signals an escalation of the ongoing conflict between the U.S. government and the nation's burgeoning medical marijuana industry.

California was the first state to pass a law legalizing marijuana use for patients with doctors' recommendations.

The four U.S. attorneys in California are refusing to provide details of the crackdown in advance. But at least 16 pot shops received letters this week warning face they would face criminal charges if the dispensaries do not shut down in 45 days.

The move comes a little more than two months after the Obama administration toughened its stand on medical marijuana.