Cairo (CNN) -- Sam LaHood, a senior representative of the U.S. International Republican Institute and the son of U.S. Transportation Secretary Ray LaHood, has been prevented from leaving Egypt, the institute said Thursday.
Sam LaHood, who directs the institute's office in Egypt, went to the Cairo airport Saturday for a routine flight, said Scott Mastic, the institute's Middle East director, in Washington.
Egyptian authorities stopped LaHood and told him that he would not be allowed to travel, Mastic told CNN.
He is one of five international staff for the institute to be prevented from leaving Egypt, said the institute's president, Lorne Craner. Three of them are Americans.
"We are deeply troubled by the fact that the Egyptian government, which is meant to be a long-standing U.S. ally, would prevent U.S. citizens from leaving Egypt," Mastic said.
The incident comes amid heightened tensions between Egyptian authorities and international nongovernmental organizations that work in Egypt.
Last month, Egyptian security forces raided the offices of several such organizations, including the International Republican Institute, chaired by Sen. John McCain, R-Arizona, and the National Democratic Institute, which former Secretary of State Madeleine Albright founded. Both groups receive money from the federal government.
The National Democratic Institute, headquartered in Washington, works to "establish and strengthen democratic institutions and practices" around the world, according to its website.
The International Republican Institute, also in Washington, works to spread democracy through the world by supporting training in such areas as good governance practices, civil society development and electoral reform, its website says. It describes itself as a nonpartisan organization unaffiliated with any political party.
The Egyptian raids were part of an investigation into allegations that the groups may have received illegal foreign funding and may have been operating without government licenses, a spokesman for Egypt's general prosecutor's office, Adel Saeed, said at the time.
Saeed told CNN on Thursday that the investigating judge had banned six people from International Republican Institute from traveling until the investigation of "receiving foreign funding" is complete.
After the United States and several nongovernmental organizations protested in December, Egypt's military rulers pledged to end the raids. They also said they would return equipment and documents that security forces had seized.
But Mastic said the International Republican Institute and other groups had not been allowed back to their offices since the raid despite promises to the contrary by Egypt's leaders and that their property had not been returned.
In addition, the institute's legal counsel in Egypt had established the travel ban was issued "by a judge in the Ministry of Justice leading the investigation against international organizations in Egypt -- the groups that were raided by the Egyptian government in December," Mastic said.
Seventeen of the institute's staff, both Egyptians and foreigners, have been interrogated by the Ministry of Justice, he said.
The institute is in close contact with the U.S. Embassy in Cairo, the State Department and Capitol Hill about the situation, Mastic said, and is attempting to have the travel ban lifted through its legal counsel in Cairo.
"We are very much concerned about our staff, and they are worried about what's going on," Mastic said.
"In three decades of IRI work, we have never faced this kind of intimidation and harassment in any country in the world," he said. "We would not expect it in a country that is the second biggest recipient of U.S. assistance."
Craner said U.S. governmental officials had told him that the people who are not being allowed to fly are among those who have been interviewed by Egyptian government judges. These sessions have lasted about four hours at a time during which staff members have been asked political questions, he said.
Some staff may not be allowed to leave the country because there could be trials as a result of the questioning, he told CNN.
"It was hard to believe they would send armed raiders to our office," Craner said. "It's hard to believe they would deny people the ability to leave the country. And I'm just wondering what the next thing is that will be hard to believe will happen."
McCain issued a statement expressing his "growing alarm and outrage" at the Egyptian government's actions.
"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," he said.
"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."
Two State Department officials said Thursday that several U.S. citizens are on a "no-exit" list after the Egyptian government raids. The officials asked not to be named because of the sensitive diplomatic nature of the subject.
The U.S. Embassy in Cairo is providing consular assistance to the Americans involved, the officials said.
Anne Patterson, the U.S. ambassador to Egypt, also is working with the Egyptian government to lift the travel restrictions so the U.S. citizens can come home, officials said.
Julie Hughes, director for the National Democratic Institute in Egypt, said it had been informed by its lawyers that six of its expatriate staff have been barred from leaving Egypt, but it had not received written confirmation of such a ban.
The ban is "distressing," she told CNN.
Hughes said seven expatriate employees and seven Egyptian staff have been interrogated by the authorities in the past month.
The United States has provided billions of dollars in aid and investment to Egypt over the past 30 years, the State Department says.
It requested $250 million in economic support funds and $1.3 billion in foreign military financing from Congress in the 2012 financial year, in support of a revitalized partnership with Egypt and Egyptians, the State Department said in an online statement in May.
CNN's Ben Wedeman reported from Cairo and Elise Labott from Washington; CNN's Laura Smith-Spark, Mohamed Fadel Fahmy and Jill Dougherty also contributed to this report.