The United Nations’ drug watchdog agency says that the legalization of marijuana in the U.S. states of Colorado and Washington poses a threat to the international fight against drug abuse.

In a report published Tuesday, the International Narcotics Control Board said that it “deeply regrets” moves by those two states to lift restrictions on the sale and use of cannabis.

The board said the moves violate drug control conventions and called on national authorities to block the states’ moves. The U.S. Justice Department has made clear it won’t go after state-legal businesses even though federal law still bans marijuana consumption.

The INCB, which has no enforcement power, has previously voiced its opposition to legalization.