Oakland — Federal prosecutors are trying to seize the properties that are home to the Bay Area’s largest medical marijuana dispensary as part of an escalated statewide campaign targeting the industry’s biggest players.

U.S. Attorney Melinda Haag has filed civil forfeiture complaints against the landlords of Harborside Health Center, which claims more than 100,000 customers, 100 employees and $20 million in annual marijuana sales.

Harborside is by far Oakland’s largest dispensary. Last year, it reported paying the city more than $1 million in taxes. It also offers yoga and acupuncture sessions and is the city’s only dispensary with a parking lot, making it a popular draw for customers across the East Bay.

“This is just a naked coming out that they’re going after the most successful players no matter how responsibly they have acted,” said Dale Gieringer, director of California NORML.

The move against Harborside, which also has a dispensary in San Jose, is the latest salvo in a crackdown against the state’s medical cannabis industry begun last October.

Federal prosecutors have forced hundreds of dispensaries to close, citing state violations for being located within 1,000 feet of schools, parks and playgrounds.

In a statement released Wednesday, Haag said she was now turning her attention to “marijuana superstores” such as Harborside that aren’t near areas where children congregate.

“The larger the operation, the greater the likelihood that there will be abuse of the state’s medical marijuana laws,” she wrote in a prepared statement.

Nearly all of the landlords targeted by prosecutors have evicted their dispensaries, medical cannabis advocates said.

Harborside’s Oakland facility at 1840 Embarcadero is owned by Anna Chretien, who runs a security firm at the same address. Chretien did not return calls Wednesday. The federal complaint estimated the property is worth $1.8 million.

Harborside posted a message on its website Wednesday that it is not in imminent danger of closing.

“We will contest the Department of Justice action openly and in public, and through all legal means at our disposal,” Harborside’s Executive Director Steve DeAngelo said in a prepared statement. “We look forward to our day in court and are confident that justice is on our side.”

Harborside has also come under attack from the IRS, which ruled last year that the dispensary couldn’t deduct typical expenses such as rent.

The state’s four federal prosecutors released a joint statement Wednesday announcing that they had sent out dozens of letters threatening to seize properties used for commercial marijuana operations, which violate federal law. They said the campaign targeted those profiting from marijuana sales rather than medical marijuana patients.

Since October, prosecutors have successfully closed several of the Bay Area’s most prominent dispensaries, including the Berkeley Patients Group. In Oakland, Coffeeshop Blue Sky, a dispensary that was controlled by medical marijuana pioneer Richard Lee, was forced to move from its original home after a school moved nearby.

The crackdown has also jeopardized Oakland’s effort to expand from four to eight dispensaries. Three of the four dispensary groups selected for permits earlier this year have struggled to find suitable homes.

It’s unclear whether Harborside would be able to find a landlord willing to offer it a new home, given that prosecutors aren’t citing it for being too close to a school, but for violating federal law, Mickey Martin of the Cannabis Warrior blog said. “It’s an escalation which is obviously scary for the entire industry,” Martin said.

Contact Matthew Artz at 510-208-6345.