Donald Trump’s administration separated more than 2,600 children from their parents without adequate systems in place to track or reunite families, according to the first government review of the controversial family separation policy.

The Department of Homeland Security (DHS) struggled to monitor and reunite families and provided parents crossing the border with inconsistent information while enforcing the “zero tolerance” policy that made family separation possible, according to the report released on Tuesday by the DHS office of inspector general (OIG).

The report painted a damning picture of different agencies unable to adequately cooperate or share data and a system that was so full of inconsistencies and holes that information on vulnerable children or their parents could easily go missing or not be collected.

“DHS was not fully prepared to implement the administration’s zero tolerance policy or to deal with some of its after-effects,” the 25-page report said.

Using information collected on unannounced visits to DHS facilities in Texas in late June – almost a week after Trump signed an executive order ending the family separation policy – the OIG found:

The main departments involved with family separation, DHS and the health department, did not have adequate information sharing systems. The OIG said it could find no evidence to support a statement made by the two departments in late June that there was “a central database” with information on separated families.

Parents were given inconsistent information and some did not understand their children would be separated from them. One parent said a border patrol agent told him he would be reunited with his five-year-old daughter after appearing in court, but when he got to court, he was given a flyer explaining he was separated from his child.

Efforts to ensure the youngest children were adequately tracked and identified were insufficient. “Border patrol does not provide pre-verbal children with wrist bracelets or other means of identification, nor does border patrol fingerprint or photograph most children during processing to ensure that they can be easily linked with the proper file,” the report said.

On 6 April, attorney general Jeff Sessions directed prosecutors at the border to adopt the “zero-tolerance” policy, ushering in mass separations of families at the border. The American Civil Liberties Union (ACLU) and other migrant rights groups had warned family separations were already taking place in the months leading up to Sessions’ announcement.

The OIG report depicted an information vacuum for tracking families and a lack of meaningful cooperation on sharing data between agencies.

“A lack of a fully integrated federal immigration information technology system made it difficult for DHS to reliably track separated parents and children, raising questions about the government’s ability to accurately report on separations and subsequent reunifications,” the report said.

Employees at the DHS agency, Immigration and Customs Enforcement (Ice), told the inspector general’s office they did not have access to data from another DHS agency, Customs and Border Protection (CBP), that identified parents who had been separated from their children. Ice said without that information, it initially did not try to identify or reunite separated parents.

CBP employees said they could not automatically send information to the health department, which takes custody of unaccompanied children, so the agency had to enter information into a Microsoft Word document and send it as an email attachment.

“Each step of this manual process is vulnerable to human error, increasing the risk that a child could become lost in the system,” the report said.

The inspector general’s office requested DHS data on family separation, but said it took weeks to receive it and once it had the information, they found it was incomplete – a determination they were able to make, in part because, they had identified separated children that weren’t included in the provided data.

A mother and son from Guatemala hold hands during a news conference on 9 July following their reunion in Linthicum, Maryland, after being reunited following their separation at the US border. Photograph: Patrick Semansky/AP

The OIG also said separated children were held for long periods in facilities intended for short-term detention, though the inspector general said this was done in facilities that complied with child detention standards.

Children are supposed to be held in CBP detention for less than 72 hours, but the inspector general found 237 of 855 unaccompanied children at the facilities they visited had been held longer then that limit. One child was held for 25 days and another for 12 days, according to the report.

Senior border patrol officials told the OIG they had less capacity to do their primary job of securing the border because they were looking after children.

The report included a response from the DHS liaison with the inspector general, Jim Crumpacker. “The draft report provides no mention of the department’s significant accomplishments to reunify families,” Crumpacker said.

Homeland security department spokeswoman, Katie Waldman, said the report’s findings “illustrate the difficulties in enforcing immigration laws that are broken and poorly written”.

“This administration will no longer turn a blind eye to illegal immigration and will continue to refer illegal border crossers for prosecution,” Waldman said in an emailed statement. “We are committed to enforcing the rule of law and ensuring that there are consequences for illegal actions.”

Lee Gelernt, deputy director of the ACLU’s Immigrants’ Rights Project and lead attorney in a lawsuit seeking reunification of separated families, said the report showed the Trump administration’s “ineptitude and historic failure of foresight”.

“Thousands of children are living with trauma because of the Trump administration’s family separation fiasco,” Gelernt said in a statement. “Some parents may never see their children again.”

OIG also released a report on Tuesday that surveyed child detention conditions. It said the nine facilities it observed in late June met government mandated standards for providing children access to toilets, sinks, drinking water, food and hygiene items

The report included photos of kitchen facilities stocked with frozen pizzas and milk containers, as well as an office that had been converted into a holding room with a crib and child-sized tables and chairs.