Accused of interference in Egypt's affairs, US pro-democracy groups whose staff are to be tried in Cairo reject charges they are working secretly for the US government, which largely finances them.

Barrie Freeman, director of the North Africa region for the National Democratic Institute (NDI), one of the US groups whose offices were raided in December, denied the NDI has a hidden agenda.

"We trained thousands of candidates, hundreds of them were from the Muslim Brotherhood and the Salafist party," Freeman told AFP, referring to Islamist groups that won a decisive majority in recent parliamentary elections.

"We don't favor any party over another. We don't fund parties directly. We don't fund revolutions. We trained poll watchers, we sent international election observers," she said.

"The program components included bringing people who had been through transition in their countries at high level.

"We brought in a former general from Indonesia, we brought politicians from Chile and Poland to share their experiences," Freeman said.

Since December, ties between the United States and Egypt's interim military rulers have become strained, and Washington has raised the possibility it could withhold military aid worth $1.3 billion a year.

"It's really puzzling," says Charles Dunne, the Middle East and North Africa director at Freedom House, another US-funded group raided in November.

"There is a campaign to try to shut down or control completely the civil society in Egypt," Dunne told AFP.

"We're involved in civic education," he said.

Egyptian authorities disagree, accusing the groups of undermining the military-run government during a fragile transition following last year's ouster of longtime ruler Hosni Mubarak, once a close US ally.

Egyptian Judge Sameh Abu Zeid said in Cairo that the NGOs are operating "without license," and that their work "constitutes pure political activity and has nothing to do with civil society work."

But the US State Department said Thursday that it has not yet seen any document outlining the charges against the groups.

If convicted, the members of these organizations could be sentenced to five years in prison, according to another judge, Ashraf Ashmawi.

Activists opposed to Egyptian military rule see the accusations as an attempt to silence them under the banner of fighting "plots" from abroad.

The US-funded groups reject the charge they are secretly working for the US government.

"It's unfair," said Eric Trager, a specialist at the Washington Institute for Near East Policy.

"If it's a foreign funding issue, these groups shouldn't be targeted exclusively, it should be the Salafist party, the Muslim Brotherhood. Egypt is a poor country. Everyone receives money from abroad," Trager said.

The NDI said it is financed up to 81 percent by the State Department and the US Agency for International Development. Its board of directors is chaired by Madeleine Albright, who was president Bill Clinton's secretary of state.

The NDI, which was present in Ukraine during the 2004 "Orange Revolution" and works on five continents, is not "affiliated" with the US government, said Kathy Gest, who is in charge of public relations.

John McCain, an influential senator and 2008 Republican presidential candidate, is the chairman of the board of directors of the International Republican Institute, also targeted by Egyptian authorities.

On its website the IRI says it is financed through subsidies from US government agencies.

For its part, Freedom House has a budget of $25 million for 2012, with $21 millions coming from the US government, according to communications manager Mary McGuire.

But for Thomas Carothers, vice president for studies at the Carnegie Endowment for International Peace, the question of financing is secondary.

"The same activities have been carried out in Belarus for at least 12 years and haven't produced very much," Carothers told AFP.

"This idea that there is some kind of sinister technology that very quietly, the US or certain European actors go into countries and prepare them for revolution, is colorful and sounds like a good spy movie."