DUP MP Jeffrey Donaldson insisted that soldiers who had fought for Britain in battle had done so "out of a deep sense of patriotism", and that such interpretation was a "poor attempt at rewriting history".

The Irish leader made the comments at last night's centenary celebrations held by the Services, Industrial, Professional and Technical Union in Dublin.

She referred to the "grim days back in 1909" when SIPTU's forerunner, the Irish Transport and General Workers Union, had been founded by Jim Larkin.

She said that the world he had lived in back then was one where "the struggle was against starvation, disease and exploitation, where the lack of education of the masses was matched only by the ignorance of the economic and political elites".

President McAleese continued: "Here was what Thomas Kettle would memorably describe, less than a decade later, as 'the secret scripture of the poor' that would drive tens of thousands of young Irish men into the British Army to sacrifice their lives so that their families could eat."

Kettle was a nationalist Home Rule politician and journalist, barrister, writer, poet and economist who died at the Somme.

Junior Minister Mr Donaldson said that any suggestion that Irishmen had joined the Army solely to alleviate their own poverty was "certainly not accurate".

He said: "Whilst there may have been some young men who joined the Army at the time because of poverty, I believe there was a majority of soldiers who took part in the First World War out of a deep sense of patriotism and a need to defend democracy and to oppose those who set out to use military methods to oppose people and nations.

"It was only after the Irish state was founded in 1921 that recruitment from the Irish Republic to the Army dropped. Prior to that there had been a long and proud history of Irish regiments playing a military role (in the British Army].

"It would be entirely wrong to suggest that this was only due to poverty. History does not recall that."

The DUP minister added: "I do think that the Irish president should give a lot more thought to what she says on occasion. Either inadvertently or deliberately, at times she uses phraseology that is a poor attempt at rewriting history."

Ulster Unionist peer and former UDR Major Ken Maginnis said that Mrs McAleese was "diminishing" the important role played by her fellow Irishmen in the war, and described her words as a "second faux pas" – her first, he said, being her comments four years ago that Protestant children were taught to hate Catholics in the same way Nazis despised Jews.

"The whole idea that men joined the Army to keep their families off the bread line is absolute nonsense," he said.

"In any case soldiers were paid a pittance in those days, so in actual fact Mrs McAleese is not only doing a disservice to Irish history, but to her fellow Irishmen, by diminishing the role they played, and indeed that they continued to play during the Second World War."

As part of its homecoming campaign coverage, the News Letter spoke to one soldier from the Republic last summer who explained that he had decided to join the Army to give himself a sense of purpose.

Former Irish Defence Force reservist Billy Heffernan, 23, from Kilkenny, joined the 1st Battalion of the Royal Irish Regiment last July.

"The English Army has a lot more to offer – I can go on to further education maybe after a few years and there are plenty of options for combat tours, going to Iraq, Afghanistan or other areas like that," he said.

"I think it will give me a personal sense of achievement to come home from these places and say to myself, 'I did that'."

A spokesman for Mrs McAleese last night said that he had "nothing further to add".