Tuesday marks the next hearing in the case of the activists, launched earlier this year after Egypt’s military council – which took power following the uprising toppling veteran leader Hosni Mubarak – accused foreign groups of funding street protests against them.

Egyptian authorities brought the case against 43 defendants –16 Egyptians and 27 foreign nationals, and at one point barred the foreigners from leaving the country.

After months of pressure from Washington, 13 of the foreign defendants – including six Americans –were allowed to fly out of Cairo airport in March after posting bail. Reports said a $5 million bail was paid for their release.

“We continue to make very clear our objection to what we view as these politically-motivated trials,” Toner told journalists.

He added that Washington urged “the government to stop trying these individuals and instead resolve any outstanding issues that they may have on this matter in a government-to-government basis.”

Mansour, who only recently obtained American citizenship, said before heading back to Cairo on Sunday that he could not abandon those Egyptians who had been left behind, and accused U.S. officials of being too passive in the affair.

“This case is extraordinary and it needs an extraordinary response,” the 32-year-old said, quoted by The Washington Post.

“They were hoping that if we all kept a low profile, it would fizzle away. But that’s not acceptable for me. This is a battle that should be fought.”

The Post said that another American, Robert Becker, 43, a former employee of the Washington-based National Democratic Institute, had chosen to stay in Cairo when the other Americans left and would also appear at Tuesday’s hearing.

“The whole idea of being safely ensconced in the United States while people who worked directly for me were on trial was unfathomable,” he told the U.S. daily recently.

“I felt they were being abandoned and I wouldn’t have been able to live with myself.”

Toner added that the United States embassy was ready to provide consular assistance to Mansour if needed for the hearing.

Among the Americans targeted by the Egyptian authorities had been Sam LaHood, the head of the U.S.-based International Republican Institute and son of U.S. Transportation Secretary Ray LaHood. It was not immediately clear whether he was returning for the hearings.