TEL  AVIV, Israel - The heads of two American pro-democracy groups in Egypt whose staff members have been barred from leaving the country say they're worried about an investigation into their activities that could lead to trial and possibly arrest.

Country director Julie Hughes of the National Democratic Institute says she is "concerned," and the International Republican Institute's Sam LaHood says there is no reason for optimism.

"I don't have any concrete reason to be optimistic at this point," he told ABC News by phone from Cairo.

LaHood is the son of  Transportation Secretary Ray LaHood. LaHood is one of six Americans, including Hughes, who cannot leave Egypt while the investigation into their NGOs is ongoing.

LaHood says the three Americans from his organization are senior management. Hughes says three Americans from NDI are trainers and election observers.

IRI and NDI are two of 17 NGOs that were raided in late December, their offices sealed off and equipment seized. They were accused of receiving foreign funds and working without official permission, something they have been trying for years to obtain from Egyptian authorities both during the era of President Hosni Mubarak and the military council that took his place last February.

Both the NDI and IRI are funded by Congress and Egyptian military officials running the country have accused foreign countries - and the U.S. in particular - of meddling.

The U.S. provides $1.3 billion to Egypt every year, part of the 1979 Camp David Accords that brought peace between Israel and Egypt.

The NDI and IRI staffers blocked from traveling only found out about it by "dumb luck," says LaHood, after he tried flying out on Saturday to visit a friend in Doha.

At passport control, he was taken aside and waited for an hour before he was told he wouldn't be traveling, by order of the immigration department. After another 40 minutes, he was given his passport back and then left in front of the airport. LaHood says other NGOs don't know if they're on the list because written notices have not been sent out. Hughes says they hope to find out more on Sunday.

Asked if he fears arrest, LaHood says his lawyer thinks it's unlikely, "but anything's possible at this point." He said a raid on their offices and a serious investigation that could lead to trial at one point seemed "ludicrous."

"I do think there's something larger at work here. There's a lot of speculation about what's behind this," said LaHood. "I find a hard time injecting logic into this situation."

Hughes says conversations between Egypt and the U.S. over the matter are going on "at numerous levels." Meanwhile she says that NDI will try to monitor elections for Egypt's upper house of parliament, the Shura Council, that are set to begin next week. LaHood says IRI will not participate.