The Trump administration’s effort to track children the US authorities separated from their families at the US-Mexico border is plagued by communication problems that raise questions about the accuracy of the data, a watchdog reported on Thursday.

The administration created the tracking system following its “zero tolerance” policy on immigration in 2018 where more than 2,500 children were forcibly separated from their parents at the southern border – though the watchdog has estimated that figure could be much higher.

Immigration officials have continued to separate some children from their parents at the border for certain reasons including a parent’s suspected criminal history, and have said the tracking system will help avoid some of the chaos, confusion and trauma suffered by separated children.

According to court figures at least 955 children were separated between June 2018 and July 2019.

But that tracking system is flawed, in part because details about whether separation from parents occurred are not automatically transmitted between federal agencies, from US Customs and Border Protection, which manages the border, to Health and Human Services (HHS), which deals with migrant children, the HHS Office of the Inspector General, reported.

The report found that Health and Human Services only discovered the 2018 separations were occurring through media reports – in part because there was no communication between agencies.

The result was chaos, with some children languishing in detention well beyond legal limits, others inconsolable in the hands of care providers who had no answers on when parents were returning. Some children were kept waiting in vans for hours in parking lots amid delays in reunification.

“Not knowing what happened to their parents haunted the children,“ one care provider told investigators, according to the report. “We couldn’t tell them whether they would ultimately be reunited.

“It was challenging. We weren’t notified initially about how to connect parents with their kids. The kids had lots of questions, but we had no answers for them.”

Health and Human Services officials said in a letter to the watchdog that it had the best interest of children at heart and was committed to improving, but that family separation is a thorny subject involving the Justice Department, Homeland Security and HHS, and there isn’t a simple fix for some issues.

Staff members interviewed by the watchdog team reported problems ranging from being unprepared with suitable facilities and personnel to care for young children in detention and difficulties matching parents back with their parents after they had been separated by the authorities.

There was no plan in place to reunited children with their parents after they had been separated, inspectors found.

One government employee said they “called [the DHS detention center] every day seeking the parents of an 11-year-old child. They could not reach anyone. The child cried every day.”

The 2018 separations occurred in part because some migrant parents were charged criminally with illegal entry and jailed – while legally the children could not be put in jail and so were detained separately.

Curbing immigration is Trump’s signature policy and with more families coming to the border and turning themselves in, while traditionally unlawful crossings had more typically been lone males looking for work and trying to evade the authorities, the administration declared itself overwhelmed.

Arrests were an effort in part to dissuade migrants from making the dangerous trek north, with families separated and tortuous court procedures, policy efforts critics decried as intentionally based on cruel intentions.

The Associated Press contributed to this report