HOUSTON (Reuters) - California refineries said on Tuesday they had started or were close to starting production of winter-blend gasoline, two days after Governor Jerry Brown authorized its sale to tame skyrocketing retail gasoline prices.

Brown authorized production of winter-blend gasoline three weeks before the normal October 31 start date. Wholesale prices declined by 60 cents on Monday, and retail prices were expected to quickly retreat. Winter-blend gasoline releases substances that contribute to smog in higher temperatures, so its sale is usually reserved for cooler weather.

The switch to winter-blend gasoline is expected to increase California's gasoline supply by 10 percent, the equivalent of adding another refinery in the state, analysts have said.

Valero Energy Corp. said its refineries in Los Angeles and the San Francisco Bay area had begun making winter-blend gasoline. Phillips 66 said it expected a quick transition to making winter-blend gasoline at its Los Angeles and San Francisco refineries.

Pipeline operator Kinder Morgan said it would accept winter-blend gasoline for shipment immediately on its 3,000 mile Pacific pipeline system. The company had originally scheduled October 15 to start accepting the fuel for shipment.

(Reporting by Erwin Seba)