Eighteen out of 69 UAE Islamists, serving jail terms for plotting to overthrow the government, are on hunger strike in protest over alleged maltreatment, Amnesty International said on Tuesday.
Six of the prisoners began their hunger strike on 31 July, and three of them collapsed between 21 August and 28 August, the rights group said.
Amnesty did not comment on when the remaining strikers started their protest.
"Their hunger strike is a protest against alleged ill-treatment by Al-Razeen Prison authorities," the London-based group said.
"They have complained of beatings by prison guards and restrictions placed on family visits. They have also highlighted light deprivation and say that prison authorities turn off air conditioning in high temperatures," Amnesty added.
The human rights group has called for immediate action to urge the authorities in the United Arab Emirates to "ensure that all detainees are protected from torture and other ill-treatment."
They have also urged the UAE to make sure that prisoners "have regular access to their families, are given any necessary medical treatment, and are held in adequate conditions of detention, including adequate ventilation and lighting in line with the Standard Minimum Rules for the Treatment of Prisoners".
In July, a UAE court jailed the 69 men for up to 15 years on charges of 'plotting to overthrow the government', at the conclusion of a mass trial criticised by rights groups.
They were part of a group of 94 defendants, including 13 women.
Prosecutors said the accused were linked to the Al-Islah group, which has ties to the Muslim Brotherhood. Political movements are banned in the UAE.