A former IRA member is to appear in a Philadelphia court on Monday after allegedly failing to disclose terrorism convictions when filling out an official US travel document.
The charges arise after Mr Joseph Black (46), from Belfast, arrived in Philadelphia International Airport last Wednesday for a niece's wedding.
The FBI said yesterday that he was to be charged with issuing a false statement on an official government document, and fraud or misuse of other documents.
The Irish American Unity Conference, a US-based nationalist support group, said that the involvement of the FBI's joint terrorism task force was totally unnecessary, and that the force did not disclose why it wished to apprehend Mr Black.
Mr Andrew Somers, a retired judge and the national president of the IAUC, said Mr Black was not a threat to the US, and should be released immediately.
FBI spokeswoman Ms Gerri Williams said Mr Black was arrested last Wednesday as he arrived at Philadelphia International Airport on a British Airways flight. She believed the joint terrorism task force was initially involved, but said that the Immigration and Customs Enforcement (ICE) was handling the case.
The arrest is the latest in a series of cases involving former republican prisoners arrested after the creation of the US Department of Homeland Security in March 2003. Most are alleged to have filled out immigration documents falsely while visiting people in the US.
Mr Black, who served three years in prison in Northern Ireland in the late 1970s, is said to have told the FBI that he no longer has any paramilitary connections.
Mr Sean McClorey, Mr Black's brother-in-law, told a Pittsburgh-based Irish-American radio show, Echoes of Erin, that Mr Black was travelling with family members for a wedding.
He said the family had since contacted the offices of the President, Mrs McAleese, the Taoiseach, Mr Ahern, Senator Ted Kennedy's office and a Pennsylvania congressman to highlight the case.