The U.S. Attorney's Office has threatened to sue Mendocino County over its money-making medical marijuana cultivation permits, county officials confirmed Wednesday.

The warning was delivered during a Jan. 3 meeting between County Counsel Jeanine Nadel and representatives of the U.S. Attorney's Office, Nadel said.

In response, county supervisors will review the pot permit ordinance on Jan. 24.

The program already has been suspended pending the outcome of a Southern California court case that questioned the legitimacy of issuing permits for medical marijuana-related endeavors.

County Supervisor John McCowen, who was instrumental in creating the county's permit ordinance, criticized the threat and the federal crackdown initiated last year against medical marijuana operations and dispensaries.

Such actions "will have the effect of driving medical marijuana back underground, making it more illegal, profitable and dangerous," he said Wednesday.

The U.S. Attorney's Office declined to comment.

Supervisors will be considering changes to the ordinance that would bring it into compliance with the current status of the Los Angeles case, McCowen said. That likely would include an end to the permits and changeover to regulations, which appear to be more acceptable to the courts, he said.

The essence of the court case is "you can regulate but you can't permit," McCowen said.

Abandoning the permits would mean a loss of income to the Mendocino County Sheriff's Office. The permits, inspections and identifying zip ties generated $663,230 for the department last year.

Last year federal officials issued letters of warning to other California cities, including Chico and Eureka. Both subsequently backed away from their ordinances.

The letter to Chico Mayor Ann Schwab noted that marijuana cultivation remains illegal under federal law and said that people who "knowingly facilitate such industrial cultivation will be doing so in violation of federal law."

In Mendocino County, some local officials, including Mendocino County Supervisor Dan Hamburg, a medicinal marijuana patient, have criticized the permit program as being too progressive for the times and bringing federal attention to the county.

It allowed medical marijuana collectives to grow up to 99 plants. The annual application and first inspection cost $1,500. Each plant was required to have an identifying zip tie, at a cost of $50 each. Monthly inspections cost between $300 and $600, sheriff's officials said.

Last year, 94 people signed up for the program.

County Counsel Jeanine Nadel said Monday she has advised Sheriff Tom Allman to suspend the program in part because the county could be required to repay the permitting fees, depending on the outcome of the Los Angeles case.

The county's pot-growing permits are popular among many marijuana growers but some have reservations. Critics say they are a tax on the sick and could trigger a lawsuit.

Marijuana growers who participate in the program had hoped it would avert law enforcement raids. But federal authorities last year raided at least two cooperatives that held county permits.

The U.S. Attorney's Office has been cracking down on medicinal marijuana cultivation and dispensaries since early last year, including issuing warnings to landlords who rent to medical marijuana dispensaries.

Americans for Safe Access, a medical marijuana advocacy group, in October filed a federal lawsuit seeking to halt the federal government's action.