Sinn Féin MP Martin McGuinness said today he was concerned at the refusal by the US to grant a visa waiver to party representative Rita O'Hare.
Mr McGuinness and Ms O'Hare met the US Ambassador to Ireland James Kenny this morning to update him on the peace process.
After the meeting Mr Guinness said the party was concerned at the visa refusal. He said Ms O'Hare has travelled to the US for almost seven years to promote the peace process. "Huge concern has been expressed by our friends int he US at the decision and many members of Congress have voiced their protest to US Envoy Mitchell Reiss and the State Department," he added.
He said: "According to a report in the Irish Timesthe reason being used to justify the decision is a change of venue for an already scheduled meeting with someone who is a key player in securing peace and democracy in Ireland.
"It is worth noting that since January Ms O'Hare has applied for and received two visa waivers to visit the US in March and April."
Mr McGuinness welcomed the announcement from the US State Department that the move did not represent a change in policy towards Sinn Féin.
It is also understood from official sources that the ban is temporary.
Mr McGuinness has been given permission to travel to New York and Washington next week and he is expected to meet State Department officials in the US capital.