Galway West TD Noel Grealish has been accused of “disgraceful racism”, of using “dogwhistle tactics” and of seeking notoriety after he suggested some money sent home by Nigerian immigrants in Ireland may have derived from crime or fraud.

Mr Grealish used the Leaders’ Questions slot in the Dáil on Tuesday to raise the issue of personal remittances sent from Ireland to other countries. He honed in on Nigeria, which in the past five years has received a total of €3.54 billion – the largest sum.

Describing the amount as “astronomical”, he said he believed a lot of the money was genuine but asked if the Department of Finance or the Revenue Commissioners had mechanisms in place to ensure it was “not the proceeds of crime and fraud”.

I remember my grandmother – all her family went to America – telling me about the cheques coming from the States

Mr Grealish was heckled by a number of TDs, including Solidarity TD Ruth Coppinger, who told him “you are a disgrace” as she accused him of “disgraceful racism”.

Taoiseach Leo Varadkar said for decades, even centuries, Irish people had gone abroad and sent money home.

“I remember my grandmother – all her family went to America – telling me about the cheques coming from the States,” Mr Varadkar said.

It is the second time in recent weeks that Mr Grealish has made controversial comments about African immigrants. At a public meeting about a proposed direct provision centre in Oughterard, Co Galway in October, he claimed the type of people to be accommodated in the centre would be “economic migrants from Africa” whom he described as “spongers”.

The latest comments by the Independent Deputy, who backs Government votes regularly, were widely condemned by political opponents and by immigrant advocate groups.

Minister for Justice Charlie Flanagan told Mr Grealish “more remittances came back to county Galway than to most other counties from the US and your constituents know that”.

Fianna Fáíl justice spokesman Jim O’Callaghan said that as an election approached many TDs wish to “get notoriety and attention”. He continued: “In doing so they should avoid picking on easy targets such as immigrants. What immigrants do with their money is none of Mr Grealish’s business. If he has evidence [of fraud] he should report that to the Garda.”

Joe Loughnane of the Galway Anti Racism Network described the comments as “dogwhistle politics of the worst kind”.