A record number of children from overseas are in US government custody as Donald Trump's administration continues to enforce hardline immigration policies.

More than 14,000 unaccompanied migrant children were being held in detention facilities this week, the Department of Health and Human Services (HHS) said. The figure tops a record set two months ago.

The rise, first reported by the San Francisco Chronicle, is thought to be largely due to increased background checks on adults who come forward to take children into care.

Immigration and Customs Enforcement (ICE) began carrying out the checks earlier this year and has used information obtained through the process to arrest undocumented immigrants who had offered homes to children.

Previous administrations did not look into prospective carers’ immigration status.

Democrat senators said the policy was deterring families from coming forward, leaving children languishing in custody.

“Right now, unaccompanied children are being held in detention facilities or living in tent cities due in part to potential sponsors’ fear of retribution from ICE for coming forward,” said California senator Kamala Harris. “This is an unacceptable obstacle to getting these children into a safe home, and we must fix it.”

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The number of unaccompanied minors in detention facilities swelled by thousands earlier this year after Mr Trump’s administration implemented a “zero-tolerance” immigration policy that resulted in parents being separated from their children at the southern US border.

HHS ended the policy in June following a public outcry, but the number of children in government custody has continued to grow steadily.

The department has been forced to erect “tent cities” to house the children because its permanent shelters are full.

An HHS spokeswoman blamed the situation on “a crisis at the border” and a “broken immigration system.”

Last month ICE confirmed it had arrested 41 people who came forward to take care of unaccompanied minors, confirming suspicions the agency was using the vetting process to track down illegal immigrants.

Democrats have proposed a bill that would prohibit immigration officials from using information gathered during the background checks to punish prospective carers.

“We will ultimately be judged as a society by how we treat our children, and without these crucial protections we are depriving unaccompanied minors of a place they can begin to call home," said Ms Harris.

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It comes as thousands migrants arrive at the US-Mexico border after travelling in a caravan from Central America.

Many are refugees fleeing poverty and violence in their home countries of Honduras, El Salvador and Guatemala.