Donald Trump‘s administration is planning to expand the collection of DNA from migrants who cross into the US, and to store the data in a huge criminal database run by the FBI.

The plan is separate from, and much broader than, the quick-fire DNA testing done on families at the US-Mexico border to catch out adults falsely posing as parents. Few details are known about the increased testing, including why it is being done or whether it would apply to unaccompanied children and asylum seekers.

Two senior Homeland Security officials said the Department of Justice was behind the new plans.

It follows a huge increase in the number of people crossing the border, mostly Central American families. Officials have since said the numbers had dropped down after crackdowns, changes to asylum rules and agreements with Central American countries, but border officers and agents have voiced concern over the potential for criminals to cross while resources are stretched.

DNA testing is done mostly through a cheek swab to collect saliva, or using a strand of hair. The proposed new scans would create an enormous trove of biometrics data, raising privacy concerns and questions about whether people should be compelled to hand over their genetic fingerprint.

'Dangerous' overcrowding of migrants in US border facilities Show all 6 1 /6 'Dangerous' overcrowding of migrants in US border facilities 'Dangerous' overcrowding of migrants in US border facilities Photos of detained migrants crowded into cells at the US border - with one holding up a sign reading simply "help" - have been released as part of a new report warning of "dangerous" overcrowding. The memo was sent to the Department of Homeland Security by its Inspector General, containing photos taken at border facilities in the Rio Grande Valley over a week in June DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Eighty-eight adult males held in a cell with a maximum capacity of 41, some signalling prolonged detention to OIG Staff on June 12 DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Overcrowding of families observed by OIG on June 11, at a border patrol facility in Weslaco, Texas DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Migrant families overcrowding a border patrol facility on June 11 in McAllen, Texas DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Fifty-one adult females held in a cell designated for male juveniles with a capacity for 40 at Border Patrol’s Fort Brown Station DHS/OIG 'Dangerous' overcrowding of migrants in US border facilities Migrant families overcrowding a border patrol facility on June 11 in McAllen, Texas DHS/OIG

Vera Eidelman, from the ACLU, said they change the purpose of DNA collection from one of criminal investigation to population surveillance, and reflected the Trump administration’s “fixation on villianising folks at the border”. People’s DNA also contains identifying information on their families.

A top Border Patrol official recently warned that expanding DNA collection at the border could make processing migrants in an orderly fashion more difficult.

Brian Hastings, chief of the Border Patrol’s law enforcement directorate, told a judge that his agents were currently not trained in the relevant collection, handling or health and safety precautions involving DNA.

Currently, people who cross the border illegally are made to give their fingerprints, which are sent to federal databases accessible by state and local law enforcement agencies. DNA can be taken if a person has been arrested on federal charges – and crossing the border between ports of entry is considered a federal crime.

Law enforcement agencies can submit samples to the FBI from suspects who are arrested or convicted of state or federal crimes and non-US citizens who are being detained by the government. The FBI’s national DNA index contained over 17 million profiles from arrestees and other offenders, as of August.

Some police departments collect samples from people who are never arrested or convicted of crimes, without a warrant, though the person is supposed to voluntarily provide a sample in those cases and not be coerced or threatened. State and federal authorities typically require a conviction or an arrest before a sample is taken.

The DNA fingerprint act of 2005 allows federal agencies to collect DNA from individuals in their custody, including those who are not American. It’s not a requirement, and Homeland Security has not vastly collected DNA samples.

In 2010, then-Homeland Security Secretary Janet Napolitano directed that people held on administrative proceedings – not detained on criminal charges – and those facing deportation proceedings would not have DNA collected.

Broader sampling “would severely strain the resources of the agency to perform its broader mission,” Napolitano wrote in a letter to then-Attorney General Eric Holder.

The new regulations would install new protocols.