UPDATE 2-Nissan boosts U.S. production of Altima sedans

(Adds details on Nissan truck plans)

DETROIT, June 9 (Reuters) - Nissan Motor Co (7201.T) said on Monday it is increasing production of its Altima mid-sized sedan because of strong demand in the U.S. market, and curbing production of trucks.

U.S. sales of Altima in May increased 38 percent from a year ago. Overall, Nissan sales were up 4.4 percent in May, a month when the U.S. market for vehicles shrank due to record-high gas prices and declining consumer confidence.

Buyers have defected from high-margin trucks and SUVs to cheaper and more fuel-efficient cars more rapidly than some automakers had expected due to high gasoline prices.

Cars, which had accounted for less than half of industry volume in 2007, surged to 57 percent in May under what Ford Motor Co (F.N) and General Motors Corp (GM.N) executives have acknowledged as a permanent shift in consumer demand.

The Japanese automaker plans to make about 2,000 more Altima sedans every month to boost monthly production of the cars to about 17,000, Nissan spokesman Brian Brockman said.

Nissan will add a third shift of Altima sedan production at its Canton, Mississippi, plant, and eliminate one shift of truck production, resulting in no net loss of jobs, it said.

When the third shift takes up full production of Altimas, expected to be in the first week of September, Nissan will be producing the sedans around the clock five days a week.

Nissan's truck production at Canton will be reduced to one shift per day, five days a week. The line produces the Titan full-sized pickup truck, the Quest minivan, Armada full-size SUV and Infiniti QX56 full-size luxury SUV.

The shift changeover is expected to begin in two weeks, with the truck shift ending in early July, Nissan said. (Reporting by Poornima Gupta; Editing by Brian Moss, Braden Reddall, Richard Chang)