Egypt's state news agency says all three judges handling the trial of 43 pro-democracy activists have recused themselves from the case that has strained Cairo's ties with Washington.

MENA said Tuesday that chief judge Mohammed Shoukry sent a notice to Egypt's appeals court declaring he and his two colleagues can not continue with the trial of the activists, who are charged with illegal fundraising and political activities. The defendants include 16 Egyptians, 16 Americans and other foreigners.

Judicial sources quote Shoukry as saying that he felt uneasy about the trial, which opened Sunday but was adjourned until April 26. The exact reason for his resignation was not immediately clear. Egypt's court of appeal typically assigns new judges to a case when the original judges withdraw.

The Obama administration has warned that it will cut $1.3 billion in annual U.S. military aid to Egypt if the trial proceeds. U.S. officials have said the American activists were trying to help the country organize its recent elections and did not engage in partisan activities.

U.S. Secretary of State Hillary Clinton said Tuesday that Washington continues to hold “very intensive discussions” with Egypt to resolve the dispute.

Egypt imposed a travel ban on the pro-democracy activists, but some left the country before the measure took effect. Several American defendants have taken refuge at their embassy in Cairo. None of the foreign activists attended the trial's opening.

A lawyer for three of the defendants told the French News Agency that judges often recuse themselves because of a conflict of interest or a sense of pressure. Hafez Abu Saada also said the appointment of new judges could lengthen the trial.