Colorado Attorney General John Suthers has warned state leaders that federal prosecutors say state medical marijuana regulators are not immune from federal statutes outlawing pot.On Tuesday, Suthers forwarded to Gov. John Hickenlooper and state lawmakers a letter from Colorado U.S. Attorney John Walsh saying that the Justice Department "does not focus its limited resources on seriously ill individuals who use marijuana as part of a medically recommended treatment regimen in compliance with state law."However, Walsh cautioned that marijuana remains illegal under federal law, and the Justice Department will continue to "vigorously" prosecute individuals or organizations engaged in "unlawful manufacturing and distribution activity involving marijuana, even if such activities are permitted under state law."Colorado is just the latest state to receive warnings from the federal government as state lawmakers consider legislation to regulate medical marijuana. Federal agents also recently raided state-sanctioned dispensaries in Montana, Michigan and California.Earlier this month, Washington Gov. Chris Gregoire said she wouldn't sign legislation to license marijuana dispensaries after the Justice Department warned it could result in a federal crackdown.The decision came after U.S. attorneys in Washington state wrote Gregoire that "state employees who conducted activities mandated by the Washington legislative proposals would not be immune from liability under the (federal Controlled Substances Act)."Montana lawmakers passed an outright repeal of medical marijuana in that state after federal raids. The repeal was vetoed, but a bill limiting marijuana dispensaries awaits Democratic Gov. Brian Schweitzer.Suthers had sought clarification from Colorado's top federal prosecutor regarding an October 2009 Justice Department memo that said seriously ill patients using medically approved marijuana treatment were not an enforcement priority. Yet, the memo warned that federal law enforcement's "core priority" remained the "prosecution of significant traffickers of illegal drugs, including marijuana, and the disruption of illegal drug manufacturing and trafficking networks."In his Tuesday letter, Walsh told Suthers that he had consulted with U.S. Attorney General Eric Holder about Colorado House Bill 1043, which would authorize state licensing of "medical-marijuana infused product" facilities with up to 500 marijuana plants and possibly grant state waivers to license even larger pot-growing facilities.Emphasizing that "there is no confusion as to the department's views on such activities," Walsh wrote that federal prosecutors "would consider civil actions and criminal prosecution regarding those who set up marijuana growing facilities and dispensaries, as well as property owners, as they will be acting in violation of federal law."State Sen. Pat Steadman, D-Denver, a sponsor of the bill, told the Denver Post that Walsh's letter only muddies the federal Justice Department's position on medical marijuana."We have had mixed messages from the federal government on this," Steadman told the newspaper. "I think this casts a big shadow upon this industry in Colorado. It does cause some uncertainty and trepidation."Walsh's letter noted that when the Justice Department issued the 2009 memo regarding 14 states with medical marijuana laws, Colorado's voter-approved Amendment 20 "authorized the possession of only very limited amounts of marijuana for medical purposes" by seriously ill patients and their caregivers.Since then, Suthers reminded Hickenlooper and state lawmakers, Colorado and other states have enacted medical marijuana regulations that "have resulted in the explosive growth in the numbers of persons claiming to be using marijuana for medical purposes." Currently, he said, the Colorado has about 123,000 registered medical marijuana patients.Suthers stressed his "great concern" about letters issued by U.S. attorneys in other states saying that state employees involved in medical marijuana regulation activities could face federal sanctions.