SEATTLE -

Washington Attorney General Bob Ferguson says cities and counties can block licensed marijuana businesses from operating.

In a long-awaited opinion Thursday, Ferguson says the state's legal marijuana law, Initiative 502, leaves local governments the option of adopting moratoriums or bans that prohibit licensed grow operations, processing facilities or retail shops from their jurisdictions.

The opinion was requested by the Washington Liquor Control Board, which has been concerned that local bans could restrict access to legal marijuana and make it difficult to move people away from the black market.

Some jurisdictions have effective bans on pot businesses, because their local ordinances require businesses to follow state, federal and local law, and marijuana remains illegal under federal law.

Nearly three dozen of the state's biggest cities have adopted moratoriums of up to a year on marijuana businesses.