The Department of Justice is planning to send immigration judges to 12 US cities to speed up deportations.

Reuters reports that the judges will be sent to cities with a high population of undocumented immigrants facing criminal charges.

The cities chosen are Baltimore; Bloomington, Minnesota; Los Angeles; San Francisco; Imperial, California; New York; Miami; New Orleans; El Paso, Texas; Harlingen, Texas; Omaha, Nebraska; and Phoenix, Arizona.

The move comes as part of President Donald Trump's promised crackdown on undocumented immigrants – with a particular target on those people who have committed crimes.

A Justice Department's Executive Office of Immigration Review spokesperson confirmed the cities named were likely to have immigration judges sent there – although no further details of the proposals were confirmed.

However, the move was called into question by former immigration judge and chairman of the Board of Immigration Appeals, Paul Schmidt, who said the plan would not necessarily result in the deportation of people.

"It seems they have an assumption that everyone who has committed a crime should be removable, but that's not necessarily true. Even people who have committed serious crimes can sometimes get asylum," Schmidt said.

There are also concerns that relocating the judges would cause a backlog in the national immigration court system – which Reuters reported has 540,000 cases awaiting hearing.