Washington's medical marijuana system is "not tenable" in light of new guidance from the U.S. Justice Department about its pot-related enforcement priorities, the chief federal prosecutors in the state said Thursday.

The warning came after the agency said it will allow the states of Washington and Colorado to move forward with plans to tax and regulate recreational marijuana sales.

In written statements, U.S. Attorney Jenny Durkan in Seattle and U.S. Attorney Michael Ormsby in Spokane promised the feds won't hesitate to go after people operating outside the legal framework set up by Washington voters last fall.

The state legalized medical use of marijuana in 1998 but never offered many options for how patients are supposed to obtain the pot. They can grow it themselves or allow someone to grow it for them, but medical marijuana dispensaries are not allowed under state law.

Nevertheless, such dispensaries have proliferated — with no oversight by state government or controls on where the marijuana comes from or where it goes. Federal authorities have raided some they deem to be fronts for criminal activity.

"The continued operation and proliferation of unregulated, for-profit entities outside of the state's regulatory and licensing scheme is not tenable and violates both state and federal law," the nearly identical statements from the prosecutors said. "While our resources are limited, we will continue to enforce federal law in this arena."

Key officials helping to create Washington state's potentially lucrative recreational pot market say its success may hinge on preventing consumers from choosing to get high on readily available medical cannabis because of low and sometimes nonexistent taxes on it.

The officials say it may be necessary to raise taxes or impose more stringent rules on medical pot to avoid undercutting the new recreational market and the tax dollars it is expected to inject into state coffers. Many "patients," they say, are in reality heavy recreational users who fake or exploit their maladies.

The idea of changing the rules for medical marijuana alarms some patients and providers of the drug as medicine.

Under current state law, a range of medical professionals, including naturopaths and even some nurses can recommend marijuana for health problems ranging from cancer to persistent pain. While Washington state has no patient registry for the drug, officials in Colorado, which also has medical marijuana, have said the overwhelmingly male and relatively young demographics of their patient population line up with statistics for recreational consumers of the drug.