The California Attorney General, armed with a sympathetic court ruling, was to seek an injunction to close up to 20 clubs, his spokesman said.
The clubs, which claim only to dispense marijuana to the sick, sprang up across the state after California voters legalised the personal medical use of marijuana. But they have been the prime target for government officials determined to nip the legalisation of marijuana in the bud.
Dennis Peron, operator of the Cannabis Cultivators Club in San Francisco, which is said to sell as much as 50lb of marijuana a week to 8,000 clients from a city centre office building, promised to defy any court order. "We're going to stay here until the tanks come," he said.
Mr Peron's club is the most visible operation, where pot is freely sold in what critics say is a party atmosphere thick with marijuana smoke. The club was raided and shut down once under orders from Attorney General Dan Lundgren, a conservative Republican now in the thick of his campaign for the California governorship.
In November 1996, a solid majority of California voters passed Proposition 215, allowing seriously ill people or their "primary care-giver" to grow and use marijuana on a doctor's recommendation.
Activists in six other states and Washington DC are pushing to put similar bills on the ballot this year, but President Clinton's administration has led efforts to contain the fall-out and prevent medical marijuana use becoming a national phenomenon.
In a hearing next month, US prosecutors will separately seek injunctions to close at least six clubs. The clubs claim that they serve as the "primary care-giver" under Proposition 215, giving them the right to supply and sell marijuana. But the California Supreme Court on Tuesday dismissed that argument after a series of appeals.
"The courts have essentially said that cannabis clubs are not allowed," said a spokesman for Mr Lundgren.
It remains to be seen how rapidly his office will move against the clubs, but there was little doubt that Mr Peron's operation is the first on the list of closures.
Mr Peron, a larger-than-life California personality, and a gay Vietnam veteran who co-authored Proposition 215, insists all marijuana is "medical".
His inflammatory statements have not endeared him to clubs in other cities, where patients are more carefully screened and which operate quietly, sometimes with the co-operation of local police.Reuse content