Trump administration officials may have lost track of thousands more unaccompanied migrant children than previously reported, according to a new analysis of federal data released Tuesday.

Last month, Department of Health and Human Services (HHS) officials told lawmakers that they were unable to account for 1,475 children who had been placed in the homes of sponsors.

But McClatchy, after analyzing HHS data, reported Tuesday that the actual number is likely closer to 6,000.

{mosads}HHS officials said originally that they completed welfare checks on 7,635 migrant children, and that 14 percent of the sponsor homes were unresponsive. According to federal data reviewed by McClatchy, the government placed nearly 42,500 children with sponsors in fiscal year 2017. Using the 14 percent figure, McClatchy estimated that about 5,945 children are likely unaccounted for.

McClatchy reported that in 2016, President Obama’s final year, more than 52,000 children were placed with sponsors, making even more likely unaccounted for.

The reports last month about the unaccounted-for children sparked significant criticism among lawmakers and the public. But federal officials have maintained that the minors they are unable to locate are not “lost.”

Officials said that the Office of Refugee Resettlement is not legally responsible for children once they have been placed in custody of a sponsor, mostly parents or other close relatives.

The office makes voluntary phone calls, or welfare checks, to the sponsors to check on the children. But officials said that since some of the sponsors are in the U.S. without legal status themselves, or have other reasons for not wanting to speak with federal officials, oftentimes they do not answer. Officials did not make follow-up calls.

Steven Wagner, the acting assistant secretary at the Administration for Children & Families, told reporters that “there’s no reason to believe that anything has happened to the kids.”

“If you call a friend and they don’t answer the phone, you don’t assume that they’ve been kidnapped,” he said, according to McClatchy. “So that characterization that the kids are missing is incorrect.”

Sponsors were even more unlikely to answer in communities were Immigration and Customs Enforcement crackdowns had recently occurred, due to what immigration advocates described to McClatchy as “a culture of fear.”

Experts also told McClatchy that the growing family separation crisis at the border is likely to further the issue of protection for unaccompanied minors.

“To the extent that there are problems for protection of unaccompanied children, this will only become worse as they put more kids in the unaccompanied category by ripping them away from their families,” Clara Long, a U.S. researcher at the international nongovernmental organization Human Rights Watch, told McClatchy.

The Trump administration is currently facing major criticism from both sides of the aisle over its policy to prosecute more illegal border crossers, leading to thousands of children being separated from their parents.