A UN expert on Wednesday urged an independent probe into allegations of torture in United Arab Emirates prisons, which she was not allowed to visit during a fact-finding mission.
Gabriela Knaul, the UN Special Rapporteur on the Independence of Judges and Lawyers, also criticised "violations" and a "lack of transparency" in court proceedings in the Gulf country, where dozens of Islamists have been rounded up.
Knaul called for independence for the UAE judiciary, which she said "remains under the de facto control of the executive branch of government."
The UAE foreign ministry welcomed her visit, pledging to "study the remarks and recommendations" she made.
But it complained that some of Knaul's comments "were based on information that had no known sources and was consistent with a politically motivated campaign by a group seeking to distort the UAE's reputation."
In her preliminary report on a nine-day visit, Knaul urged the UAE to "establish an independent committee to investigate all allegations of torture and ill-treatment in detention."
She told a press conference she had received "credible information and evidence" that detainees are arrested without warrant, blindfolded, taken to unknown places and held incommunicado, sometimes for months.
She said she also had evidence of detainees being "tortured and/or subjected to ill-treatment" including by being put in "electric chairs."
She said she was not allowed to visit prisons or meet with certain detainees, adding that "on one occasion, I was followed."
The UAE has not seen any of the widespread protests that have swept other Arab states since 2011. However, authorities have cracked down hard on dissent and calls for democratic reform, drawing criticism from human rights groups.
The top UAE security court last month jailed a group of 30 Emiratis and Egyptians convicted of forming a Muslim Brotherhood cell for terms ranging from three months to five years.
The 10 UAE citizens in the group were among 69 nationals jailed in July for up to 15 years on separate charges of plotting to overthrow the government.
In her report, Knaul said supreme court rulings must be subject to appeal, criticising "an apparent lack of transparency during both the investigation phase and court proceedings."
She spoke of claims that "evidence is sometimes manipulated and fabricated by the police or other security agencies and the prosecution."
"The lack of transparency is compounded when the court hearings are not public," she added.
Only selected relatives of the defendants, in addition to local journalists and representatives of human rights groups were allowed to attend the Islamists' trial.
Knaul also accused the UAE of "disturbing" treatment of women "who dare to file a complaint for sexual assault."
In July, a Norwegian woman was released following a pardon by Dubai ruler. Although she had filed a rape report with police, the woman found herself tried and jailed for extramarital sex, perjury and consuming alcohol without a licence.
The UAE, which is home to millions of expatriates, must also "redouble efforts to allow access to justice, in particular to vulnerable groups, such as migrant and domestic workers," she said.
It should provide "quality interpretation and translation for non-Arabic speakers at all stages of legal proceedings."
In 2010, the appeal of 17 Indian expatriates sentenced to death after being convicted of killing a Pakistani was repeatedly delayed for lack of an interpreter, drawing strong criticism from Indian human rights groups.
The court later commuted the death sentences to two years in prison followed by deportation.