Minister for Foreign Affairs Charlie Flanagan has said that "tens of thousands'' of undocumented Irish in the US could benefit from president Barack Obama's immigration reforms.

He said the president’s initiative represented progress, albeit with further important steps to be achieved.

“I am happy that progress is real and I am determined that as many Irish nationals as possible will benefit from these changes,’’ he added. In all, he said, there were an estimated 50,000 undocumented Irish in the US.

Mr Flanagan was replying to Dáil questions from Sinn Féin spokesman Seán Crowe following the revelation that Taoiseach Enda Kenny had appealed to Mr Obama for immigration reform affecting undocumented Irish to be as “open and flexible’’ as possible.

The Minster said while the president’s initiative was important and positive, there was no substitute for legislation enacted by the US Congress.

The Government, embassy staff and immigrant groups would continue to work with the US administration. Engagement would continue with political contacts, he added.

“We will keep building on our network of friends on Capitol Hill.”

Mr Flanagan said while he did not wish to raise expectations on the issue, the president’s initiative was undoubtedly a step in the right direction.

It represented, he said, real and substantial progress and was an acknowledgement of the very hard work undertaken over a long number of years, particularly in recent times, by a number of people.

All sides of the House had expressed a deep-seated interest in dealing with what had been a traumatic experience for tens of thousands of undocumented Irish in the US who had been unable to return to visit their families in Ireland and attend funerals and weddings, said Mr Flanagan.

Independent TD Denis Naugthen said it was critical to get clarity on the travel issues arising from the reform.