Intense security marked the start of court proceedings against 94 detainees in the United Arab Emirates' capital of Abu Dhabi.
The detainees are accused of trying to overthrow the government. They are also accused of being political activists connected with Egypt's Muslim Brotherhood, which is banned in the UAE
"They launched, established and ran an organisation seeking to oppose the basic principles of the UAE system of governance and to seize power," Attorney General Salem Saeed Kubaish said in a January statement published by state media.
Their trials started Monday amid widespread scrutiny of how the UAE would handle the proceedings.
Only local media were allowed inside the court, where only two members from each detainee's family were allowed in. Others had to wait outside.
Asma Al-Siddiq, 26, said both her husband and her father were among the 94 detainees accused.
"The proceedings taken by the court today are not fair," she said. "The women were forced to remove their niqab (face cover). My sister had to remove her niqab to get in. My brother Ibrahim Al-Siddiq was arrested today while in his car ... for having a badge with a picture of the detainees on it."
"My brother's arrest today is a complete act of oppression towards us," she added.
Mohammed Al-Naimi's brother is also facing the charges.
"They kept extending his detention with no reason," Al-Naimi said.
The trial began the same day John Kerry arrived in Abu Dhabi on his first visit to the Middle East in his new role as U.S. secretary of state.
Human Rights Watch released a statement calling for Kerry to address the plight of the 94 detainees, claiming 64 had been held at undisclosed locations for up to a year and denied access to lawyers until the last two weeks.
The group claims the detainees include two prominent human rights lawyers, Mohammed al-Roken and Mohammed al-Mansoori, as well as judges, teachers and student leaders.
"Emirati citizens have a lot to fear when their government can detain them without charge for months and then deny them due process in trials that can't be appealed," said Sarah Leah Whitson, Middle East director at Human Rights Watch. "Secretary Kerry should urge UAE authorities to end these shameful practices and ensure a fair trial for these activists."
Of the 94 defendants, 10 are still at large and are being tried in absentia, the state news agency WAM reported.
The court adjourned Monday to consider the pleas entered so far, WAM said. Another hearing is set for March 11.
Many believe UAE authorities are clamping down on freedom of expression since the Arab Spring swept across the Middle East staring in early 2011.
Unelected ruling families in oil-rich Gulf countries such as Barhrain, Qatar, Saudi Arabia and Kuwait have sought to prevent popular uprisings. But countries such as Bahrain have also received criticism for their heavy-handed use of force.
While there has been little protest in the majority Sunni and hugely wealthy UAE, authorities are taking no chances.
Political parties and demonstrations are banned in the UAE, and last week an academic from the London School of Economics and Political Science was barred entry to the country.
The academic was set to speak at a conference on the political situation in Bahrain.