A dissident republican councillor, Mr Francie Mackey, has criticised the decision to deny him a visa to visit the US. He was due to join Ms Bernadette Sands McKevitt, sister of the dead IRA hunger-striker Bobby Sands, who is on a speaking tour of Irish-America.
They are both members of the republican group, the 32 County Sovereignty Committee, which opposes the Belfast Agreement. Mr Mackey, a councillor in Omagh, Co Tyrone, was expelled from Sinn Fein earlier this month for criticising the leadership.
He was due to join Ms Sands McKevitt, vice-chairwoman of the committee, in New York and Washington where she has several speaking engagements and meetings planned with members of Congress.
He said he was "very disappointed" with the decision to deny him a visa and claimed it was made for "clearly political reasons". Mr Mackey has a conviction for assaulting an RUC officer.
A spokeswoman for the US embassy in Dublin said it did not discuss individual cases.