The UN refugee agency has condemned David Cameron's proposed immigration laws over fears they could stigmatise foreigners, deny housing to people in need and create a "climate of ethnic profiling".

In a highly critical document, the office of the United Nations high commissioner for refugees, António Guterres, raised concerns that the immigration bill will damage communities and lead to the marginalisation of refugees and asylum-seekers.

It comes after Tories reacted angrily to the UN's special investigator on housing, Raquel Rolnik, who warned earlier this year that the bedroom tax was causing "shocking" hardship in parts of the UK.

Cameron has proposed the immigration bill in order to crack down on illegal immigrants, restricting access to bank accounts and private housing, as well as forcing temporary migrants to pay for public services such as the NHS.

However, the commissioner is worried that legal refugees and asylum-seekers will be caught up in the new restrictions, as landlords, GPs and banks will find it difficult to interpret their immigration status. The commissioner said these protected groups would suffer discrimination if the legislation went ahead.

"The provisions of the bill appear likely to result in asylum-seekers, refugees and beneficiaries of subsidiary protection being stigmatised in the public mind and in their being denied access to housing or bank accounts," the UNHCR said in a briefing note to MPs.

"The UN high commissioner for refugees is concerned that if introduced, such measures could contribute towards a climate of misunderstanding and ethnic profiling that could undermine the longer-term prospects for integration of such persons and prove detrimental to social cohesion.

"Additionally, the UN high commissioner for refugees is concerned that the types of documentation carried by asylum-seekers, refugees, beneficiaries of subsidiary protection and stateless people can be varied and complex, and landlords and other service providers are likely to misinterpret the legality of their status.

"It will also impose an additional administrative burden on them. These challenges may have unintended consequences such as the denial of housing and other services to asylum-seekers, refugees, beneficiaries of subsidiary protection that result in their marginalisation and inhibit their integration in the United Kingdom."

The UNHCR, which is currently working with 10 million refugees in disaster zones such as Syria, also raised concerns about changes to the UK legal system after Theresa May, the home secretary, said she wanted to make it easier for illegal immigrants to be deported before they have the chance to appeal.

The Home Office declined to comment specifically on the UNHCR's concerns.

However, a spokesman pointed to a statement from October by Mark Harper, the immigration minister, saying: "The immigration bill will stop migrants abusing public services to which they are not entitled, reduce the pull factors which draw illegal immigrants to the UK and make it easier to remove people who should not be here."

Labour has said it backs some principles of the immigration bill but will try to amend some of the details. During scrutiny of the legislation, Helen Jones, a shadow Home Office minister, said she was concerned that British citizens from black or ethnic minority communities would be targeted for checks by banks and GPs "even though they may well have been born here".

"The worry I have is that if someone comes in from a black or ethnic minority background, the bank will not know whether they have leave to remain in the UK. The suspicion is that the bank will say 'produce a document' – a passport or whatever. "What will happen if that person does not have a passport?" she said. In response to the UNHCR, David Hanson, shadow immigration minister, said it was "disappointing that the government has voted against Labour's proposal to pilot this scheme and will instead plough on regardless".

"We've said repeatedly that whilst it's important that people who are here illegally are found and removed from this country, there are concerns over the workability and efficacy of these proposals."

The Home Office has been forced to defend the immigration bill against accusations it will turn GPs, banks and landlords into the equivalent of border guards by forcing them to carry out immigration status checks.

Earlier this month, the home affairs committee warned that millions of landlords may be unwilling to rent properties to immigrants if coalition proposals requiring them to carry out immigration checks were put into practice.

The cross-party group said the measures were designed to create a hostile environment for illegal migrants and could discriminate against all immigrants, regardless of their status.

They also said it would be "wholly wrong" to introduce health charges to access the NHS for those who are in Britain through no choice of their own, such as refugees and the victims of trafficking.