According to the Food and Drug Administration (FDA), in the U.S. there are no scientific grounds for the medical use of use of marijuana and the agency is highly critical of attempts by individual states to legalise it.
Marijuana remains a Schedule I drug in the U.S. under the Controlled Substances Act, the most restrictive schedule and last year the U.S. House of Representatives rejected a bill allowing the medical use of marijuana.
The agency has come out with the statement in response to requests from lawmakers and advocates to legalise marijuana and has itself come under heavy criticism for making what many see as a political decision.
The FDA maintains it will continue to support medical research into the medical use of the drug.
The medical use of marijuana has been a long contested issue at state and federal level as many patients with diseases such as cancer, multiple sclerosis, nausea, severe pain and other conditions, contest that marijuana provides them with relief, and many doctors support that claim.
The U.S government claims that FDA-approved drugs, including a synthetic form of the active ingredient in marijuana, are adequate for these patients and the Drug Enforcement Administration and prosecutors are viewing the medical marijuana movement as simply an attempt to legalise the recreational use of the drug.
The statement by the FDA appears to ignore a comprehensive report in 1999 by the Institute of Medicine, a part of the National Academy of Sciences, the nation's most prestigious scientific advisory body, where marijuana was found to be "moderately well suited for particular conditions, such as chemotherapy-induced nausea and vomiting and Aids wasting".
As many as 11 states in the U.S. have rejected the law and have over-ridden state legislature and others are in the process of legalising the use of marijuana.
The supreme court ruled in 2005 that the federal government can overrule such state laws and continue prosecuting patients, doctors, and other providers.
The FDA has expressed concern and says such measures are inconsistent with efforts to ensure that medications undergo the rigorous scientific scrutiny of the FDA approval process and are proven safe and effective and no animal or human data supports the safety or efficacy of marijuana for general medical use.