The feds are using DNA testing to make sure that migrant children separated from their parents at the border are actually related as they struggle to comply with court-ordered deadlines to reunite families.

Health and Human Service chief Alex Azar said Thursday that the testing was needed because information from children was often unreliable and because migrant adults may be lying in order to exploit children.

The DNA testing will be done using cheek swabs of every child before matching him or her with a parent.

“It’s important to remember that information from children can at times be unreliable,” Azar said in a conference call with reporters.

He also said that the usual method of verifying a parent’s claims, such as tracking down birth certificates or other documents, would take too long to meet the deadlines.

But Azar insisted that HHS would do its best comply with a federal judge’s order that children from birth to age 4 be reunited by Tuesday, and that those aged 5 to 17 be reunited with a parent, relative or guardian by July 26.

The DNA testing was first floated by administration officials and immediately came under fire from advocates for immigrants, who raised privacy concerns.

But an unnamed administration official told CNN that the tests were necessary.

“The safety and security is paramount, and it is not uncommon for children to be trafficked or smuggled by those claiming to be parents,” the official said.

“This is a cheek swab and is being done to expedite parental verification and ensuring reunification with verified parents due to child welfare concerns.”

Azar also revised upward the number of migrant children being held to “under 3,000,” a week after saying the number was closer to 2,000.

And Azar warned that entire families may remain in the custody of immigration authorities for extended periods, even those who are claiming asylum.

Before the Trump administration’s “zero tolerance” policy, migrants seeking asylum under US laws were often granted temporary release as their cases were resolved.

Azar called the deadlines “extreme” but said HHS would comply after an extensive effort to identify children in its shelters who were separated from their parents, to confirm parentage, and to screen parents for criminal violations or other problems that could result in harm to kids.

Azar also blamed Congress, the courts and migrant parents themselves for the administration’s child separation policy — and repeatedly refused to say how many had been reunited with their families.

“The simplest way to avoid this is to follow our laws, and respect our border,” he said before defending his department.

“While I know there has been talk of confusion, any confusion is due to a breakdown in our immigration system and court orders. It’s not here,” Azar said.

Azar hailed the department for the “excellent” care the detained migrant children were receiving and boasted that HHS “knows the identity and location of every minor in our care.”

“We are meeting the needs of unaccompanied alien children in our custody,” he said.

“They’re providing excellent care in a safe supervised environment with access to athletics,” he said, adding that they get “three meals a day plus two snacks.”

Asked at least three times how many children had been reunited, Azar would not provide a number.