Sinn Féin leader Gerry Adams has described the US state department's approach as "not helpful".

Mr Adams met US state department officials in Washington following confusion on Monday around whether the department had refused to host him.

“My first speaker’s lunch and meeting with President Clinton was 20 years ago today. US policy since then has been built on inclusivity and dialogue,” he said. “The approach of the state department in recent days has been at odds with this, and has not been helpful.”

However, he said the meeting yesterday was “useful and positive”.

US president Barack Obama has said there is "still more work to do" on bringing political stability to Northern Ireland.

Mr Obama said the Stormont House Agreement offered “great hope for resolution of some long-standing challenges there”. He was speaking to reporters in the Oval Office after his St Patrick’s Day meeting with Taoiseach Enda Kenny.

"There is still more work to do, but we very much appreciate the leadership that the Taoiseach has shown in this process and the collaboration with the United States in encouraging both parties to arrive at peaceful resolutions that can lead to more prosperity and growth in Northern Ireland, " Mr Obama said.

Economic recovery

Referring to the Republic, Mr Obama hailed Ireland’s economic recovery: “Ireland is on the move after a very challenging financial crisis.”

Asked after his meeting with Mr Obama what the president had said about Northern Ireland during their bilateral, Mr Kenny said: “He expressed his understanding that there’s a bit of an obstacle here, but I explained to him that I expect this can be dealt with.”

Mr Kenny said the Stormont House Agreement was “signed and acceptable” before Christmas and it was now time for northern leaders to sort out “whatever little obstacles” remained. The Government stood ready to help.

Speaking at the Shamrock presentation ceremony at the White House, Mr Obama sent a message of support to Northern Ireland First Minister Peter Robinson and Deputy First Minister Martin McGuinness.

“Two people who were going to be here are at home hammering out the details to implement the [Stormont House] Agreement,” he said. “So we wish them good luck and God speed.”

Mr Adams attended the White House shamrock-giving ceremony and stood at the back of the East Room during the speeches.

Waiver system

Meanwhile, Mr Adams said his party supported the introduction of a waiver policy for undocumented Irish.

Mr Adams raised the issue when he met the Friends of Ireland Congressional Caucus before Mr Kenny attended the traditional St Patrick’s Day lunch.

“Sinn Féin understands that if this waiver system was introduced, it would benefit over 25 per cent of the Irish citizens currently undocumented,” Mr Adams said.

“I have spoken to the US ambassador in Dublin about this scheme, and I have written formally to him. I see no obvious reason why the same waiver scheme could not be introduced for Irish citizens.”

Mr Adams said he would also be raising the matter with Mr Kenny. “Specifically, I want to know if the Irish Government has formally asked the US embassy in Dublin or the Obama administration about this waiver scheme.”

The handling of IRA sex abuse allegations made by Maíria Cahill and Paudie McGahon was not raised at the meeting with the members of Congress.

Separately, New York-based publisher Niall O’Dowd said his comments about the need for a more “aggressive” approach to immigration reform were aimed at the US embassy in Dublin.

He criticised what he described as the embassy’s “continuation of the enforcement of the blanket three and 10-year bar on returned undocumented”.