An Egyptian court on Sunday adjourned the trial of 16 Americans and 27 others who for pro-democracy groups until April 26.
Thirteen Egyptian defendants were in court for the opening hearing. They were held in a metal cage, as is customary in Egyptian trials.
Of the 16 Americans charged in the case, seven have been banned from leaving Egypt. They were not in court Sunday.
The NGO workers have been charged with operating without a license and using illegal foreign funds to foment unrest.
Hundreds of lawyers and reporters crammed into a chaotic Cairo courtroom as the trial of those who work for pro-democracy groups opened in the Egyptian capital.
The case has severely strained Cairo's relations with Washington, and U.S. officials have threatened to cut off $1.5 billion in aid to Egypt if the dispute is not resolved.
The NGO workers have been charged with operating without a license and using illegal foreign funds to foment unrest.
Secretary of State Hillary Clinton, who arrived in the Moroccan capital after visits to Algeria and Tunisia, has met Egypt's foreign minister Mohamed Kamel Amr twice in the last three days, the official said on condition of anonymity.
Retaliation?
Rights campaigners say the case is retaliation by Egypt's ruling generals against pro-democracy groups that have been among the army's harshest critics since it took power when Hosni Mubarak was overthrown a year ago.
"The whole basis of this case is unfair," an Egyptian activist working for one of the organizations told Reuters.
The U.S. pro-democracy groups whose staff have been charged deny they have done anything illegal. They say the crackdown is an attempt by Egypt's military rulers to derail democracy.
Egypt says the case is a judicial matter and all groups must heed Egyptian law.
Negad al-Borai, a lawyer representing the accused in Cairo, said the charges referred only to a short period in the groups' activities and could therefore be argued against.
"The charges made involve only the period from March 2011 to December 2011," he told Reuters. "These groups have applied for permits before that period."
Some Egyptian officials have linked the funding of civil society initiatives to a U.S. plot to undermine Egypt's sovereignty — accusations the United States and the civil society workers deny.
Among those accused is Sam LaHood, Egypt director of the International Republican Institute and the son of the U.S. transportation secretary.
The crisis escalated on Dec. 29 when Egyptian authority swooped the offices of American groups International Republican Institute and the National Democratic Institute, confiscating documents and computers and cash on the premises.
The government and the ruling military council say the case was initiated by the judiciary and is out of their hands.