The Supreme Court in Abu Dhabi last month sentenced more than 50 people to prison for associating with a group charged with plotting to overthrow the government. The International Federation for Human Rights, known by its French initials FIDH, said several prisoners have been waging a hunger strike from prison since late July.
FIDH President Karim Lahidji said he was concerned about legal standards in the United Arab Emirates.
"Judicial procedures sanctioning fundamental, legitimate human rights such as freedom of expression and association are unfair," he said in a statement. "All of those convicted solely on the basis of exercising these rights should be freed and the charges against them dropped."
A report from Amnesty International released in July said it appeared the convictions were politically motivated. Most of those sentenced were associated with the Muslim Brotherhood, a conservative Sunni political organization.
The prosecution of suspected al-Qaida members in the United Arab Emirates in April sparked similar criticism.