The Home Office is preparing to deploy facial recognition technology at transport hubs and public events as part of the biggest immigration enforcement crackdown in British history.

Policy documents show the government has been developing a programme to deploy live facial recognition (LFR) cameras for “general immigration enforcement”, including non-criminal immigration offences.

The technology will be used to identify people “seeking to re-enter the UK unlawfully”, target those subject to removal action and to crack down on broader “immigration-related criminality”.

The Home Office states the cameras will be used to locate undocumented people so it can resolve their cases, which it says will reduce “disruption to the wider public compared to repeated enforcement visits at residential addresses or workplaces”.

The documents further suggest that people could be included on LFR watchlists for overstaying a visa without permission, or entering without leave, all of which are considered civil rather than criminal matters.

The developments are contained in a new guidance document for immigration enforcement officials published on 8 October and a data protection impact assessment made public later in the month.

Their publication follows the decision by Shabana Mahmood, the home secretary, to double the budget for immigration enforcement and boost its workforce by 60% to allow “tens of thousands” more raids, arrests and deportations.

Between November last year and February, immigration enforcement conducted three trials of LFR technology at Holyhead port in north Wales.

The trials were narrowly focused on locating people travelling to the UK from Ireland through the common travel area in breach of deportation orders or on a warrant for “an immigration-related criminal offence”.

The documents suggests that, in the future, individuals “liable to detention under immigration legislation” and who have “failed to comply with immigration conditions of entry or stay” could also be put on a watchlist. The LFR project “has now moved into the formal delivery phase”, it is said.

Locations where immigration enforcement could deploy facial recognition cameras have also been expanded to include “proactive” deployments at transport hubs and at “specific” events which are “expected to increase footfall at a location”, although no specific geography is named.

A list of potential higher-risk deployments includes locations with “heightened community sensitivity”. When the Home Office was asked for clarity on what was meant by “events” or “sensitive” locations, it refused to comment.

A spokesperson confirmed that it was “considering further trials” of LFR by immigration enforcement officers and that it was “actively exploring the potential benefits, implications and future use of the technology”.

The new policy document states no one under the age of 18 will be included on a watchlist. Earlier this year it was revealed that the Home Office had continued to use an AI facial-age estimation tool despite knowing it had misidentified child migrants as adults.

Campaigners have called the “secretive” expansion a “huge and shocking escalation of mass surveillance” and highlighted the well-documented bias towards misidentifying people of colour when used at some settings.

Griff Ferris, a spokesperson for the Joint Council for the Welfare of Immigrants, said immigration enforcement already employed tactics that “persecute and terrorise migrant communities” and that giving it more power to use a “racist mass surveillance tool in public places is frightening”.

Sarah Lasoye, of the Open Rights Group, said immigration enforcement “appear to be giving themselves the green light to expand use of highly controversial facial recognition technologies without scrutiny, transparency or public consent”.

She said: “Immigration enforcement and police forces are exploiting an absence of national legislation regulating uses of AI technologies, including facial recognition, in the public sector.”

The policy documents claim the use of LFR by immigration enforcement “is subject to external oversight, including by the biometrics and surveillance camera commissioner and the Information Commissioner’s Office”.

The biometrics and surveillance camera commissioner, William Webster, told Liberty Investigates, which first uncovered the new policy documents, that he was not consulted on the policy and clarified that the use of LFR for immigration purposes fell outside his remit.

He added that the “proliferation of LFR into different service contexts does raise important questions about the scope of existing regulatory oversight”, which he hopes will be addressed in the forthcoming legislative framework for facial recognition.