Mr Phillips will tell Manchester Council for Community Relations in a speech on Thursday: "We are a society which, almost without noticing it, is becoming more divided by race and religion. Our ordinary schools ... are becoming more exclusive and our universities are starting to become colour-coded with virtual "whites keep out" signs in some urban institutions."
Other campaigners agreed that there was increased segregation, but added that the poor white community was feeling equally disenfranchised.
Ms Harman said: "We don't want to get into a situation like America, but if you look at the figures, we are already looking like America - in London, poor, young and black people don't register to vote."
The Government is to fund a hard-hitting campaign to persuade more young people, the poor and blacks to register to vote in next May's local elections.
Ministers fear that the failure of many to register is evidence of their disengagement from civic society - in the same way that the poor of New Orleans lacked a voice or power to improve their position.
Latest figures show that 20 per cent of people aged 20 to 24; 20 per cent of all those living in inner London; and 38 per cent of those in unfurnished rented accommodation were not on the register. A Bill to encourage registration is being introduced next month and Ms Harman said she could not rule out compulsory voting.
Peter Hain, the Northern Ireland Secretary, said Mr Phillips' warning had to be taken very seriously. "I want to see, as he does, more and more integration right across the board."
The chairman of the CRE proposes controversial measures including forcing "white" schools to take larger numbers of ethnic minority pupils to aid integration.
In an assessment of the UK after the July 7 terror attacks, Mr Phillips added: "We are sleepwalking our way to segregation. We are becoming strangers to each other and leaving communities to be marooned outside the mainstream."
The number of people of Pakistani heritage in ghettos, defined as areas with more than two-thirds of any one ethnic group, trebled between 1991 and 2001.
Ashok Viswanathan, founder of Operation Black Vote, said: "We have a less alarmist approach. There are these patterns emerging, but it is important to keep a sense of perspective." He said it was also important to remember the number of communities that continued to coexist happily. "There is an element of disenfranchisement but it is not just the black minority and ethnic community. It is wider than that, young people in general."
Mohammed Afzal Khan, of the Muslim Council, added: "We need to encourage better understanding and more interaction but these comments seem slightly over the top. We need to make sure the lower spectrum - and that includes poor white people - have better opportunities provided for them."
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