LOS ANGELES — Unable to rein in hundreds of medical-pot shops that blossomed around the nation's second-biggest metropolis, the Los Angeles City Council banned them Tuesday until the state's highest court weighs in.

Mayor Antonio Villaraigosa was prepared to sign the ordinance, according to his spokeswoman, Vicki Curry. The storefront ban would then go into effect after 30 days. In the interim, letters will be sent to as many as 900 dispensaries advising them of the ban.

Many cities have struggled with medical-marijuana ordinances, but none has had a bigger problem than Los Angeles, where pot shops have proliferated.

At one point, the city ordered closure of the shops — a process that failed amid lawsuits and conflicting rulings by appellate courts.

This time around, the city has a stronger case if faced with lawsuits by pot-shop owners, city officials said. A recent appellate-court ruling seems to support the new ordinance that refers to a marijuana collective as three or fewer people.

The ban also allows hospices and home-health agencies to provide medical pot.

Despite California voter approval in 1996 for medicinal use of marijuana with a doctor's recommendation, the state Supreme Court has decided to clarify marijuana's hazy legal status by addressing whether local governments can ban medical-marijuana clinics. But a hearing has yet to be set by the high court.

Meanwhile, U.S. authorities have cracked down on pot clinics around the state, saying such operations remain illegal under federal law.