Republican Sinn Féin President Ruairi O Bradaigh has been refused a visa to visit New York for a book launch.
Mr O Bradaigh - a key figure in republican politics since the 1950s - is the subject of a new biography by an American university professor.
Dr Robert W White's 350-page work on the life of Mr O Bradaigh is already on sale in Ireland and was to be launched at the weekend in New York.
"The proposed weekend visit to New York was intended solely for the book launch, surely a political act which has now been suppressed by the US Department of State,'' a spokesman for RSF said.
Mr O Bradaigh served as chief of staff of the IRA, as president of Sinn Féin and was elected -- as an abstentionist in the 1950s -- to the 26-County Dail parliament.
He took part in peace talks involving the IRA leadership and Protestant churchmen in 1974 which were opposed by the Dublin government.
In 1983 he was succeeded as president of Sinn Féin by Gerry Adams and when the party ended its policy of abstention from the Dail in 1986, he led a walk-out to form Republican Sinn Féin.
In 2004, the US State Department announced it was adding the Continuity Army Council, as well as Republican Sinn Féin, to its list of foreign illegal organisations.
The move comes after two Provisional Sinn Féin representatives were refused visas to travel to the US to attend a Hunger Strike commemoration.
The book, entitled Ruairi O Bradaigh: the Life and Politics of an Irish Revolutionary is by Robert W White, Dean of the Indiana University School of Liberal Art, and published by Indiana University Press.
* The Continuity IRA has accused the B&Q retail chain of supplying the British military in the North of Ireland. B&Q stores have been hit by five CIRA firebomb attacks in recent weeks.
In a coded thelephone call, the CIRA threatened to escalate its campaign in the run-up to Christmas and warned that B&Q was a "legitimate target".