The Home Office is selling the services of its immigration officials to private companies in a move attacked as an escalation of the “hostile environment” strategy.

According to internal documents seen by the Observer, the department is attempting to embed immigration officers at a rate of almost £60 an hour as part of an “enhanced checking service” being offered to public services, understood to include NHS trusts and local authorities, as well as private firms.

The organisations are offered “real-time” access to information about someone’s immigration status through an “on-site immigration official”, who can be asked to attend interviews and encourage undocumented migrants to leave the country voluntarily. The embedded official can also pass the details of undocumented migrants to immigration enforcement officers.

There were demands on Saturday night for the Home Office to reveal how many officers had so far been deployed and to provide a list of organisations that had used them.

Migrants’ rights experts warned that the service was the latest example of the government “trying to embed immigration checks in every aspect of life in the UK”. They warned that such schemes undermined the trust of the public and risked discouraging migrants from getting services that they desperately needed.

A presentation marked “official – sensitive” reveals the department spent at least 18 months testing “the benefits of placing immigration officials in a number of organisations”. The embedded officers are asked to ensure that migrants are either charged for services or denied access to them should they fail to prove they are in the country legally.

The Home Office charges organisations £58.20 an hour for one officer. It claims the hosts can make back the cost by charging for or denying services where appropriate.

“Ensuring that immigration status checks are conducted prior to an individual obtaining benefit or services is an essential part of ensuring illegal migrants cannot access public services to which they are not entitled, encounter a compliant environment which encourages [voluntary] departure and limit the harm they cause to the taxpayer,” the document states.

Facebook Twitter Pinterest As home secretary, Theresa May promised to create a ‘hostile environment’ for illegal immigrants. Photograph: Andrew Yates/Reuters

“We already have a core offer of free (mainly online) guidance and checking services to private and public sector organisations. The majority of these extensive free services aim to provide a response within two to five working days. However, they do not always meet the needs of our customers.

“Over the last 18 months we have tested the benefits of placing immigration officials in a number of organisations … This service can be tailored as required, but it centres on an immigration official being located within an organisation.”

The Home Office said the programme had been in place since 2016 and had been offered to “partner organisations, including local authorities and private sector organisations”. Information given to the Observer suggests the service has also been offered to NHS trusts. The department said that 13 officers were currently deployed under the programme.

Many public bodies are obliged to check the immigration status of their users. Such checks are a key part of what Theresa May described in 2012 as a “hostile environment” for undocumented migrants. Sajid Javid, the home secretary, has since described the hostile environment concept as “unhelpful”.

David Lammy, the Tottenham Labour MP who led the criticism of the Windrush generation scandal that saw British citizens threatened with deportation, said: “Sajid Javid announced he had paused the hostile environment in July, but this shows it is being ramped up.

“The Home Office should come clean about the details of this secretive scheme, and explain how it justifies spending £58.20 an hour to fill our hospitals and councils with border guards.”

Diane Abbott, the shadow home secretary, said: “This Tory government is not fooling anyone by rebranding their hostile environment policies as a ‘compliant environment’. By gathering information in this way the Home Office is creating distrust in our public services, and risks deterring vulnerable families from accessing vital support.”

Satbir Singh, the chief executive of the Joint Council for the Welfare of Immigrants, said: “Spreading the tentacles of this hostility ever deeper into our hospitals and public services is a chilling new development. It will push people away from engaging with public services, create fear in our workplaces and heighten vulnerability to exploitation.

“Sajid Javid should concentrate on building a Home Office that people can trust instead of just rebranding the same unfounded hostility.”

Colin Yeo, a leading immigration barrister, said the document showed how the Home Office was trying to embed immigration checks “in every aspect of life in the UK”. He added: “These checks are profoundly un-British and the impact on lawful but undocumented residents is disastrous, as the Windrush scandal showed.”

Facebook Twitter Pinterest David Lammy said the Home Office should ‘come clean’ about the operation of the scheme. Photograph: Stefan Rousseau/PA

Corey Stoughton, advocacy director for human rights group Liberty, called for the complete separation of migration control from vital services. She accused the Home Office of making “a side business out of seconding immigration officers into local councils and social services”.

Lucy Jones, director of programmes at Doctors of the World, a charity which offers healthcare to undocumented migrants in the UK, said: “It’s imperative that healthcare services are allowed to be neutral, safe spaces that everyone in need of treatment can go to without the risk being arrested.”

A Home Office spokesperson said: “We are committed to a fair and humane immigration policy which welcomes ... people here legally, but which tackles illegal immigration and prevents abuse of benefits and services. On-site immigration officials provide support to partners to assist their understanding of the immigration system and can conduct status checks at the request of a local authority to ensure those that are eligible for support are receiving it.”