The federal government is criminalizing use of products that contain the Southeast Asian plant kratom, which can create opioid-like effects, saying it is an "imminent hazard to public safety."

The Drug Enforcement Administration temporarily placed the main active ingredients of kratom — mitragynine and 7-hydroxymitragynine — into schedule I. That is the same classification for illegal drugs such as heroin, marijuana and cocaine.

The DEA said in a Federal Register notice that a substance can be temporarily placed on the schedule if there is an "imminent hazard to the public safety."

Products containing kratom, which is a tropical tree found in Southeast Asia and is in the coffee family, are "easily obtained from smoke shops and over the Internet," the DEA said. Products seized by law enforcement include a powder/plant, capsules, tablets, liquids and a drug patch.

"The consumption of kratom individually, or in conjunction with alcohol or other drugs, is of serious concern as it can lead to severe adverse effects and death," the DEA said.

U.S. poison centers received 660 calls related to kratom from January 2010 to December 2015, the DEA pointed out. Of those calls, 428 were for isolated exposures to kratom, but there were also reports of the drug being used with other substances such as benzodiazepines and acetaminophen.

The Food and Drug Administration also has warned against consuming kratom products.

The DEA added that it isn't aware of any "currently accepted medical uses" for kratom in the U.S.

But some critics say the move is not based on sound science.

"With the federal intent to place the herb and its bioactive constituents on Schedule I, the DEA is ignoring the increasing scientific literature on a potential beneficial medical use of the plant," wrote pharmacologist David Kroll in Forbes.

He said kratom has beneficial properties that include managing chronic pain without the side effects and potentially addictive nature of opioid painkillers. Kroll added that the July report about poison center calls from the Centers for Disease Control and Prevention has been called inconsequential due to the small number of cases compared to other legal and illegal substances.

The DEA said it doesn't have to hold a public comment period because the temporary action is not a federal rule.