The Drug Enforcement Agency announced Thursday that marijuana will remain a Schedule I drug under the Controlled Substance Act, thus declaring it is a "dangerous" and illegal drug without an acceptable medical use.

"At this time," the DEA said, "the known risks of marijuana use have not been shown to be outweighed by specific benefits in well-controlled clinical trials that scientifically evaluate safety and efficacy."

The DEA made the announcement in response to two petitions aiming to reschedule marijuana.

The agency said it will allow more researchers access to study the marijuana plant. The DEA has one authorized marijuana growing facility in Mississippi.

The official decision by the DEA will be published in the Federal Register on Friday.

At least 25 states and the District of Columbia have approved the use of medical marijuana.

According to the DEA, "Schedule I drugs, substances, or chemicals are defined as drugs with no currently accepted medical use and a high potential for abuse. Schedule I drugs are the most dangerous drugs of all the drug schedules with potentially severe psychological or physical dependence."