Call it one of the disadvantages of being a newcomer to the United States.

Eager to work, no matter what the job is, some immigrants are not aware of what legal rights they have.

There are employers who are fully aware of your lack of knowledge, and the end result is that they use it to their advantage.

"That is when people are most vulnerable to being exploited, when they are new to the system and might not fully understand what rights they have," said Ana Guajardo, head of the Centro de Trabajadores Unidos, a group based in the South Chicago neighborhood that currently has two lawsuits pending on behalf of immigrant workers.

Guajardo was familiar with several new studies on the issue, including one by the Chicago-based Working Hands Legal Clinic -- which said there was a 60 percent increase in the number of wage theft complaints filed during the first six months of 2009, compared to the same time period in 2008.

But she said the problem is not a new one, despite the sharp increase experienced earlier this year.

"This is an ongoing problem, these companies are too eager to take advantage of their workers," said Guajardo, adding that her group is working on behalf of two groups of immigrant employees to try to ensure that companies provide the same job conditions and protections to these non-citizens that they provide to any other worker.

Earlier this year, the united workers' center publicly approached businesses in the South Chicago and East Side neighborhoods, asking them to voluntarily sign a pledge that they would respect the rights of their employees.

The problem is not limited to this area.

Some state and local governments are finding that employers who do not pay overtime or minimum wage are likely not paying into state workers' compensation or unemployment insurance funds -- which hurts local taxpayers as well as the employees.

The Associated Press reported that the Los Angeles-based National Day Laborer Organizing Network said that at least half of the roughly 120,000 day laborers on any given day experience some form of wage theft.

About 68 percent of all low-wage workers reported wage theft last year, regardless of their citizenship status, according to a study that surveyed 4,400 low-wage workers in Chicago, Los Angeles and New York.

"It's not confined to the margins or a few rogue employers. Employers realize that workers are desperate," Nik Theodore told the Associated Press. Theodore is a University of Illinois at Chicago professor who cooperated with academics at the University of California at Los Angeles and the City University of New York to compile the study.

"It looks like standard business practice in many industries," Theodore said.

Of late, the federal government is taking some actions to try to address the issue.

Labor Secretary Hilda Solis approved the addition of about 250 wage and hour inspectors, and also recently signed an agreement with the labor department in New York and the Mexican consulate to create a call center providing Latino employees working in the New York metropolitan area information about their labor rights.