By Lisa Baertlein

LOS ANGELES (Reuters) - The Los Angeles City Council unanimously voted on Tuesday to put a one-year ban on new fast-food restaurants in one of the city's poorest areas, marking the latest effort by a municipality to fight rising obesity rates.

If approved by the mayor, the ordinance would put a moratorium on construction of new fast-food outlets in a 32-square-mile (82-sq-km) area of Los Angeles. The measure could also be extended for a second year.

The change would affect about half a million Angelenos living in an area that supporters say already has about 400 fast-food eateries and few grocery stores or other outlets for fresh, healthy food.

The 13-0 vote came about a year after research found that roughly 30 percent of children living in the South Los Angeles, West Adams, Baldwin Hills and Leimert Park areas are obese compared to about 21 percent in the rest of the city.

The moratorium would also be accompanied by moves to encourage more grocery chains and fresh food stores to open for business, supporters said.

Fast-food chains opposed the measure, saying that their industry was being unfairly blamed for causing the childhood obesity epidemic.

"Obesity is principally related to what and how much a consumer eats, not where he eats," Andrew Puzder, Chief Executive of Carl's Jr parent CKE Restaurants Inc, said in a letter to Council President Eric Garcetti.

Andrew Casana, spokesman for the California Restaurant Association, said fast-food companies were working to block ordinance or to make amendments to it.

"We have not ruled out lawsuits," Casana said.

Several U.S. cities have adopted measures forcing the restaurant industry to adopt healthier standards. California banned the sale of soft drinks in middle and elementary schools in 2003 and a new law requires fast-food restaurants in New York to post calorie counts above the service counter.