He said he believed there were “too many” immigrants coming into the country.

“But the ones I worry about are the Africans,” he said, "We can’t be taking in people from the Congo and all these places. I think there's too many from those places.”

Mr Ahern also said he was not concerned about the current generation of Muslim people but was worried about the next generation.

He has since said he has “no problems” with people from Africa or the Congo, as he admitted he should not have made comments about Muslims while canvassing.

Call for apology

“Words matter, and it is important that his words are clarified,” Cynthia Ní Mhurchú said. She said she had been “surprised and saddened” by the comments.

Ms Ní Mhurchú said she respected Mr Ahern, was fond of him, and believed the comments were “out of character”.

“I just would ask Bertie to consider issuing an apology. It's really important in the current climate that we're in that words that are spoken are clarified to the nth degree, and I appreciate Bertie has gone to great lengths to explain the context of what he said, and I've listened to the full interview that was recorded without his permission," she told RTÉ Radio’s Morning Ireland on Thursday.

"But nonetheless the words as they stand themselves are not words that represent my views and my opinions . I agree with the Taoiseach that we can't be calling out a certain ethnicity , we cannot be calling out a certain race or a certain country . It is very unhelpful and, as I say, I was extremely surprised and saddened.

"I really would like if an apology was issued by him because apologies do matter particularly in the current climate," Ms Ní Mhurchú added.

Comments 'deeply disturbing'

Speaking in the Dáil on Thursday, Labour leader Ivana Bacik called the comments "deeply disturbing" and said that it came on the back of a candidate in the same by-election, Gerry Hutch, calling for internment of Somalian migrants.

"Particularly alarming was the way in which he singled out specific ethnic, religious, and national identity," Ms Bacik said of Mr Ahern's comments.

"More than being just offensive and irresponsible, this language was dangerous and inflammatory for a politician who devoted so much of his career to finding a resolution to the Troubles, a conflict based in religious division.

"It's shameful to hear him refer to a child's religion, Islam, when he says he's worried about the next generation of Muslims."

Ms Bacik said it was "profoundly wrong to use language which could direct public anger towards migrants and minorities.

"We've already seen a candidate in that constituency make an outrageous call for internment of refugees, and in the other by-election, in Galway West, a torrent of despicable online racist abuse has been directed at our Labor candidate, councillor Helen Ogbu."

Ms Bacik said that wider government migration policy is "failing the people whose work is building our community".

Tánaiste Simon Harris said he "deplores" any abuse suffered by any candidate and that Mr Ahern's comments were "not appropriate".

"I want to be very clear in relation to the comments of the former taoiseach; they weren't appropriate. They were wrong. It's absolutely, perfectly legitimate in this country — in fact, it's essential — that we debate migration. No one has an issue with that. It's important we debate it.

"We can have sensible and rational discussions around migration policy. Every country in the world is having that.

"It's never acceptable to single out an entire group of people based on their race, based on their ethnicity, or indeed, based on their religion. That only serves to demonise or to stigmatise people. That's not a helpful contribution."

Mixed reaction within Fianna Fáil

Earlier, party colleague and Dublin City councillor Niall Ring described the incident as “gotcha politics at the lowest level” and “a storm in a teacup.”

Mr Ring said it was important to consider the comments in the “overall context”.

“If we start cancelling and looking for apologies based on a 10-second clip taken out of context, nobody would be safe from the woke brigade," he said.

“It's really a storm in a teacup. What Bertie was saying actually reflects the concerns and the realities. He was speaking bluntly about the speed and scale of migration, and it's the reality he was talking about . If the political establishment isn't able for the reality, they should look at themselves," Mr Ring added.

He acknowledged that the comments about Muslims and the Congo were “probably ill-judged”.