The Home Office is reviewing the rules over the access failed asylum seekers and illegal immigrants have to the NHS.
It is estimated that 390,000 failed asylum seekers could be affected.
According to the Observer newspaper, they may be barred from all but emergency health services.
The paper reported that a think tank says up to 390,000 failed asylum seekers could lose access to free care if the plans are approved.
The Home Office said it is reviewing "the rules governing access to the NHS by foreign nationals".
But it added that no definite proposals had been put forward.
The review, conducted jointly by the Home Office and Department of Health, is due to be published in the New Year.
Currently everyone in the UK qualifies for free primary health care services, such as access to GPs.
The Observer reports the Institute for Public Policy Research (IPPR) think-tank says such a move would create problems for illegal immigrants and the health service.
Jill Rutter, senior research fellow at the IPPR, told the newspaper: "This will increase community tensions. What signals are going to be sent out if queues of asylum seekers are waiting at A&E departments because they can't register with a GP?
"The government is in danger of normalising what many people will see as a breach of human rights - someone's right to basic health care provision.
"The government is saying people who aren't entitled to healthcare should pay for it but asylum seekers are the very people who can't afford to pay for these services."