A south Belfast estate agent has confirmed he has been warned against letting properties to black or Chinese families.
Mr William Faulkner, whose office on the Donegall Road was damaged in a petrol bomb attack in June, said he had been approached and warned.
However, Mr Faulkner told The Irish Times he is still renting to immigrant families, although he informs them of the risks.
"I warn them what has been going on," he said last night. "And if they're prepared to rent, I'm prepared to go through with it."
He accepted that additional police officers are now addressing the racism issue, but accused the PSNI of acting too late.
Mr Faulkner's comments were made amid fresh reports of activity by the National Front and Combat 18, another anti-immigrant group, in south Belfast.
Politicians and churchmen have united in condemnation of the latest attack on a Pakistani family in the Village area of the city on Wednesday night, and some have been critical of the police response.
PSNI figures reveal that 212 racist incidents occurred in the eight months before Christmas, a dramatic rise on the previous year.
Ms Geraldine Rice, an Alliance councillor and member of a District Policing Partnership, said: "It is no secret that the UVF has been involved in extortion rackets focusing on Chinese-owned businesses in south Belfast, and that the Ulster Defence Association has been infiltrated by far-right groups like Combat 18 in the Village area.
"Together these groups have engaged in the abuse and ethnic cleansing of minorities in south Belfast," she claimed.
However, the Progressive Unionist Party leader, Mr David Ervine, said the UVF had no policy of involvement. "As to whether there are any individuals involved on a paramilitary level, I do not know and that is something we need to look at."
He added: "They are the lowest of the low and we have got, as a people, to come to terms with what creates these conditions in which these scumbags think it is wise for them to do what they are doing."
Sinn Féin also joined in the criticism of the police, accusing officers of refusing to identify the groups responsible. Mr Alex Maskey, a south Belfast assembly member, said: "The first thing we need to do is to identify the source of these attacks. But the PSNI wont say which paramilitary group is involved."
He claimed that violent attacks were concentrated on a small number of streets in south Belfast and that police had gone to a small number of houses advising people to leave.
Last night a PSNI representative declined to be drawn into claims about the level of paramilitary involvement. However the PSNI confirmed that patrols have been increased in response to the spate of attacks and denied it has recommended to some Village residents that they move.
The DUP's Mr Sammy Wilson, a former lord mayor, rejected accusations that many in the local community were racist.
He said he knew numerous people from immigrant communities. "Many of them would happily testify that the majority of people in Northern Ireland have welcomed them and treated them fairly and as equals. It is deplorable that a small, warped minority are presenting an image of Northern Ireland that bears no reality to the true face of the province."
The Rev Martin Smyth, MP for south Belfast, which includes the loyalist Village area, said of the attackers: "If these people think their actions are for the benefit of their community, then their reasoning is mistaken and perverse."