Updated 10:50 a.m. ET: Senator John McCain (R-AZ), for whom Sam LaHood worked during the 2008 presidential campaign, on Thursday expressed "outrage" at the development.
In a statement, he said: "It is worrying enough that Sam and his fellow NGO workers have been singled out by name in Egyptian state-owned media; it is outrageous that these individuals would be held against their will by Egyptian authorities and prohibited from leaving the country. These individuals and the organizations that employ them have broken no laws, and indeed, have made every effort to comply with the statutes, regulations, and requests of the Egyptian government."US working with Egypt to lift travel ban on NGO workers 'in merest days'
Sen. McCain added: "I call on the Egyptian government and the Supreme Council of the Armed Forces to cease the harassment and unwarranted investigations of American NGOs operating in Egypt, to register these groups immediately, to return all of the property confiscated in the raids against these organizations, to end the intimidation of their employees by Egyptian officials, and to permit those members of these groups who wish to leave the country to do so. I deeply regret that this crisis has escalated to the point that it now endangers the lives of American citizens and could set back the long-standing partnership between the United States and Egypt."
Published 6:20 a.m. ET: Egypt's authorities have imposed a travel ban on four members of a U.S.-funded pro-democracy organization — including the son of U.S. Transportation Secretary Ray LaHood — in a row over its activities, a source said Thursday.
A member of an NGO with knowledge of the case told Reuters Thursday that the four members of the International Republican Institute (IRI) include three U.S. citizens. One is Sam LaHood, who is the IRI's Egypt director.
"It is a de facto detention," the member of a non-governmental organization (NGO) in Cairo told Reuters, requesting anonymity due to the sensitivity of the case.
The Department of Transportation told NBC News it is not commenting on the Secretary's son not being allowed to fly out of Egypt.
The judges investigating the case have charged the four with managing an unregistered NGO and being paid employees of an unregistered organization, charges that could carry up to five years in jail, he said. The IRI had no immediate comment.
The group is in Egypt and has been forbidden to travel outside the country.
Pro-democracy groups raided
The New York Times reported Sam LaHood was prevented from boarding a flight last week, citing IRI officials.
The officials told the paper that other American staff were also told they were not allowed to travel outside Egypt.
The Times said that the move appeared to be an escalation of a criminal investigation by the Egyptian authorities into groups with foreign funding that have been promoting democracy.
The U.S. expressed deep concern in December after Egyptian police raided offices of U.S.-backed pro-democracy and human rights groups, including the IRI, saying the harassment should stop immediately and hinting that Washington could review its $1.3 billion in military aid if the raids continue.
Egyptian prosecutors police raided offices of 17 pro-democracy and human rights groups in what rights defenders described as a campaign against them by the military rulers.
Speaking after those raids, State Department spokeswoman Victoria Nuland described them as "inconsistent with the bilateral cooperation we have had over many years".
She said U.S. officials had been in touch both with Egyptian Prime Minister Kamal al-Ganzouri and with Egypt's ambassador in Washington to underscore Washington's concern
The IRI, which is loosely associated with the U.S. Republican political party and receives U.S. government funding, says it takes a neutral political stance, fostering democracy in Egypt by training members of nascent parties in democratic processes.
Reuters contributed to this report.