Federal authorities said Wednesday that they plan to seize the Oakland property used by Harborside Health Center, which is believed to be the nation's largest medical marijuana dispensary.

The U.S. Attorney's Office for the Northern District of California posted a notice on Harborside's door this week, saying it intends to seize the property under federal laws prohibiting the distribution of marijuana.

Harborside generated $21 million in sales in 2009 alone and claims over 100,000 patients.

Its size made it a target, said Melinda Haag, the U.S. Attorney for the Northern District of California. She called the famed dispensary "a superstore."

"The larger the operation, the greater the likelihood that there will be abuse of the state's medical marijuana laws and marijuana in the hands of individuals who do not have a demonstrated medical need," she said in a statement.

The property, which federal authorities said was valued at around $2 million, is owned by Ana Chretien, owner of ABC Security, one of the East Bay's most politically powerful security companies. Her company has had contracts with the city of Oakland, Alameda County and the Port of Oakland, including Oakland International Airport.

Chretien could not be reached for comment.

Harborside's attorneys said the center has done nothing wrong. They said they found the forfeiture notice taped to their doors Tuesday.

"Nobody gets into Harborside without a recommendation from their doctor," said attorney Henry Wykowski.

Wykowski and several others noted that U.S. Attorney General Eric Holder has said federal officials would not go after dispensaries that were complying with state law.

"Size is not the determining factor," said Wykowski. "The attorney general said they weren't going to go after dispensaries that were in compliance with state law. We're in compliance. We pay our taxes. The state has never complained."

James Anthony, another Harborside attorney, said the motive was clear.

"They're doing it because they want to shut Harborside down," he said. "It's not clear where else in Oakand that Harborside could go."

The forfeiture notice at Harborside is the latest blow to the medical marijuana industry in Oakland, the political center of cannabis politics in the state. Oakland has only four permitted dispensaries, part of a concerted effort to keep a relatively tight rein on an industry to which other cities give a wide berth.

But Harborside is the second Oakland dispensary to be targeted by federal authorities this year. It comes three months after federal authorities raided and shut down a dispensary, school and other properties connected to Richard Lee, the founder of Oaksterdam University, a training ground for people who want to work in the marijuana industry. Lee was the state's most active proponent of marijuana legalization but has been out of business ever since.

Oakland authorized four more dispensaries earlier this year. But three of the dispensaries have yet to open, in part because of landlord fears about federal property seizures. Hundreds of dispensaries have been shut down around the state in a growing federal crackdown.