COLUMBIA - At least 350 children caught at the U.S. border this year have been sent to stay with relatives or other sponsors in South Carolina, according to federal data released Thursday.

They are among more than 30,000 children who have been sent to sponsors nationwide from Jan. 1 through July 7. That's according to data published Thursday by the Department of Health and Human Services' Administration for Children and Families.

Rumors that undocumented minors were being housed in South Carolina surfaced last week, sparking protests around the state. In response, Gov. Nikki Haley released a letter she sent to Department of Homeland Security Secretary Jeh Johnson.

"I also greatly appreciate your confirmation that there are currently no shelters or facilities - military or otherwise - in South Carolina being used to house the minors who are being abandoned at the border with Mexico, and your assurance that there are no current plans to use any South Carolina facilities for this purpose in the future," Haley wrote in the July 17 letter. "I do ask that if those plans are developed at any point going forward that you personally notify me immediately of any shift in policy."

Haley went on to say South Carolinians have the right to know who the federal government is relocating to the Palmetto State.

Concerning Thursday's announcement that 350 migrant children were being housed in South Carolina, Haley's office said federal officials will not provide governors any additional information, including the children's ages, where they are or how they arrived.

In all, 30,340 unaccompanied children have been released to sponsors in 2014, often to their parents. The vast majority were from El Salvador, Guatemala and Honduras.

The federal government must place the children in the least restrictive setting while they are involved in immigration proceedings, under terms of a class-action lawsuit settlement in 1997. The Administration for Children and Families said it tries to place children with a parent, relative or family friend, in that order.

Sponsors undergo background checks that include a search of criminal records and are responsible for making sure a child shows up for court, the agency said. The sponsors' immigration status is not considered.

More than 57,000 unaccompanied children were arrested by the Border Patrol from October through June, mostly in the Rio Grande Valley in south Texas, according to Thursday's report.

The surge has led the government to open temporary shelters at military bases in San Antonio; Ventura, Calif.; and Fort Sill, Okla. and to search nationwide for new shelters to hold children until they are released to sponsors.

Texas took in 4,280 of the children through July 7, followed by New York with 3,347, Florida with 3,181, California with 3,150, Virginia with 2,234 and Maryland with 2,205, according to Thursday's report.

The Post and Courier's Dave Munday contributed to this report.