Welfare benefits for the children of illegal immigrants cost America's largest county more than $600 million last year, according to a local official keeping tabs on the cost.

Los Angeles County Supervisor Michael Antonovich released new statistics this week showing social spending for those families in his county rose to $53 million in November, putting the county government on track to spend more than $600 million on related costs for the year -- up from $570 million in 2009.

Antonovich arrived at the estimate by factoring in the cost of food stamps and welfare-style benefits through a state program known as CalWORKS. Combined with public safety costs and health care costs, the official claimed the "total cost for illegal immigrants to county taxpayers" was more than $1.6 billion in 2010.

"Not including the hundreds of millions of dollars for education," he said in a statement.

Antonovich's figures, though, center on costs generated by American-born children of illegal immigrants. Isabel Alegria, communications director at the California Immigrant Policy Center, said it's "unfair" to roll together costs associated with both illegal immigrants and U.S.-born citizens.

"Those children are U.S. citizens, children eligible for those programs," Alegria said.

She also questioned the authenticity of Antonovich's numbers regarding health care and public safety -- though for the welfare program statistics, Antonovich cited numbers from the county's Department of Public Social Services.

Antonovich acknowledges that the children whose benefits he's focusing on are U.S.-born. But he argues that the money is collected by the illegal immigrant parents, putting a painful burden on taxpayers, including those who are legal immigrants.

"The problem is illegal immigration. ... Their parents evidently immigrated here in order to get on social services," Antonovich spokesman Tony Bell said. "We can no longer afford to be HMO to the world."

He said the state should cut back on these social benefits. According to the November statistics, that cost accounted for 22 percent of all food stamp and CalWORKS spending in the county.

Over the summer, the Federation for American Immigration Reform also looked at these kinds of costs nationwide to get an idea of the burden to local governments at a time when many are grappling with budget deficits.

The organization reported that the cost of illegal immigration stands at about $113 billion a year. Nearly half of that amount went toward education costs, according to the study. Costs were naturally higher in states with large illegal immigrant populations -- in California, the total annual cost was pegged at $21.8 billion.