These communities are among the most discriminated against in the NHS, according to a DoH consultation launched as part of its Pacesetters Programme, which aims to tackle health inequalities.
It says that 'GPs often do not accept members of these communities onto their lists or refuse treatment', leaving them to seek help through A&E services.
But BMA ethics committee chairman Dr Tony Calland said that any blame should be directed at PCTs, not GPs.
'The practice hands over the registration form to the patient, but the decision rests with the PCT.
'It may be that the PCT has difficulty registering a patient without an address, but that is something for the trust to sort out.'
He also called for PCTs to design local enhanced services so that practices can offer healthcare to people living in encampments.
Dr Calland added that GPs should not turn away anyone who is in need of urgent medical care, even if they are not registered.
The DoH consultation, which closes on 2 June, also highlights discrimination across the NHS against gay, lesbian and transgender patients.
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