Speaking alongside Mr Kenny at a joint press conference in Boston's City Hall during which the Taoiseach said "it's not just about the Irish", Mr Walsh said while he is a "proud" Irish-American he cannot support anything that would "just benefit one country".

In his first speech as part of a week-long St Patrick's Day trip to the US on Saturday night, Mr Kenny told the Friendly Sons of St Patrick organisation in Philadelphia that speaking up for the 50,000 Irish illegally living in the US would be one of his "absolute priorities" when he meets Mr Trump on Thursday.

However, while welcoming the comments, Mr Walsh - who has repeatedly challenged Mr Trump's zero tolerance policy on illegal immigration, and staunchly opposes both the Muslim travel ban and attacks of US sanctuary cities - said any deal would be irrelevant if it failed to also help people from other countries who are being similarly targeted.

"I'm a proud son of Irish immigrants, but I would not be supportive of rules and regulations that just benefit people who are undocumented Irish.

"As mayor of Boston I have an obligation to represent all of the people in our city and that means all of the countries here. So I couldn't support something that just benefited one country," he said.

Asked if he was "heartened" by the fact Mr Trump's de facto Muslim travel ban - which is due to come into effect on Thursday, as Mr Kenny meets the president - has now been watered down, Mr Walsh said he continues to have the "same concerns" that led him to label it "un-American" earlier this year.

He said he was "not heartened at all" by the climb-down as it was "a very minor change, one country was taken off the list, and the fears in the city still exist, the painting of immigrants as criminals and Muslims as terrorists are still out there", before insisting his city will continue to be a sanctuary city regardless of what actions Mr Trump threatens to take.

The comments are likely to influence Mr Kenny's approach to Thursday's meeting with the US president, due to ongoing calls for him to take a tough stand on Mr Trump's controversial immigration policies for both Irish and other people.

While he has until now failed to specifically outline whether his focus on illegal Irish immigrants will also see him speak out on behalf of illegal US immigrants from other nations, addressing the same question after Mr Walsh spoke Mr Kenny said "I don't agree with blanket bans on any country".

"We need the opportunity for a path to legitimisation here, but it's not just about the Irish. It's not just in the case of Ireland, but also many others.

"It's not a case of picking and choosing. There are 11 million people in the US who do not have the required documentation," he said.