SAN FRANCISCO – An Oakland medical marijuana dispensary that has been billed as the largest pot shop on the planet has been targeted for closure by federal prosecutors in Northern California, suggesting that a crackdown on the state’s medical marijuana industry remains well under way.

U.S. Attorney Melinda Haag has threatened to seize the Oakland property where Harborside Health Center has operated since 2006, as well as its sister shop in San Jose, executive director and co-founder Steve DeAngelo said Wednesday.

His employees found court papers announcing asset forfeiture proceedings against Harborside’s landlords taped to the doors at the two locations on Tuesday.

Although medical marijuana is legal in California, a federal court complaint that Haag’s office filed Sunday says the dispensaries are violating federal law by selling marijuana.

It cites a federal law that “makes it unlawful to rent, lease, profit from or make available for use, with or without compensation, a place for the purpose of unlawfully manufacturing, storing, distributing or using a controlled substance, to wit, marijuana,” as justification for going after the landlords.

The court action represents an escalation in a months-long, statewide crackdown on medical marijuana by Haag, who said last year that she would try to shut dispensaries that were within 1,000 feet of schools, parks and playgrounds, which Harborside isn’t.