The criticisms of illegal immigrants made by Fianna Fáil Cork North Central TD, Mr Noel O'Flynn, and others in recent days were neither "educated", nor "tolerant", the Taoiseach, Mr Ahern has declared.
Last week, Mr O'Flynn said illegal immigrants were "spongers" and "freeloaders", who were "thumbing their noses at Irish hospitality and demanding everything under the Geneva Convention".
Meanwhile, SIPTU general president, Mr Des Geraghty is to investigate similar criticisms made by a Cork-based union official, Cork Corporation Councillor Joe O'Callaghan.
The union has sought a transcript of a 96FM debate in which Cllr O'Callaghan said that parts of the city had been overrun by foreigners.
Mr Geraghty told The Irish Times: "We are very concerned about it.
If there were any incitement we would be very concerned about it. The policy of this union is totally against racism."
Facing Dáil demands to censure Mr O'Flynn, the Taoiseach said: "Needless to say, I reject those comments and since he is a member of my party I have already made that clear."
Concerned at the drift in public debate, he said: "People need to look at the broader picture of what happens. It is easy to raise racial issues.
In my view, anybody who does that to satisfy a group in one area should be extremely conscious of what a group in another area feels. It is not an educated or tolerant view."
The Taoiseach is understood to have spoken to Mr O'Flynn about his comments, though the Cork TD did not withdraw them when he spoke in the Dáil shortly after Mr Ahern.
Then, Mr O'Flynn said: "I have been vocal about anti-social behaviour and crime on our streets since I first entered politics. Am I now to be silenced because some of those causing the problem are illegal immigrants?"
However, he emphasised that he had criticised illegal immigrants, and not proper asylum seekers.
"My remarks are aimed at the many illegal immigrants who are causing hostile public reaction because of their anti-social behaviour and abuse of Irish hospitality," he said.
Despite Fine Gael TD, Mr Alan Shatter's charge that he is fomenting racism, Mr O'Flynn said he had first expressed his reservations about immigration policy two years ago.
"I have seen nothing since to cause me to change my mind about illegal immigration. I will continue to express the concerns expressed to me daily by my constituents.
I have received many telephone calls regarding anti-social behaviour by some illegal immigrants on the north side of Cork city," he told the Dáil.