Former UN rights chief Mary Robinson has been accused of supporting the emirate of Dubai's version of events over a princess who was feared missing.
Mrs Robinson, who recently met Sheikha Latifa, daughter of Dubai's ruler, said she was a "troubled young woman".
She told the BBC the princess regretted making a video in which she alleged confinement and torture.
Radha Stirling, head of the rights group Detained in Dubai, said questions remained about the princess's welfare.
"Anyone familiar with Princess Latifa's story who listened to the BBC Radio interview today with Mary Robinson will be astonished at the extent to which Mrs Robinson appeared to be reciting almost verbatim from Dubai's script," she said.
"What we heard today was Mary Robinson essentially reciting for BBC Radio listeners the content of the statement issued by the Dubai ruler's court."
She added: "This meeting in no way satisfies me that she [Sheikha Latifa] is free from the abuse that she told me she had suffered for years."
What's the background?
Sheikha Latifa, the daughter of the emirate's ruler Sheikh Mohammed Bin Rashid Al Maktoum, is said to have tried to flee abroad in March in order to live a freer life.
But campaigners say the luxury yacht she was fleeing on was intercepted off India, and she was forcibly returned to Dubai, one of the United Arab Emirates (UAE).
A video emerged - filmed following an earlier escape attempt - in which the princess said she and her family "did not have freedom of choice" in their lives. She also alleged she had been imprisoned for three years and tortured on her return.
The UAE denied the reports, and said Sheikha Latifa had been living at home with her family.
But when the princess was not heard of for months, international human rights groups asked the authorities to prove her safety.
On Monday, the UAE foreign ministry said it had sent a communiqué regarding Sheikha Latifa to the UN human rights office.
It released images showing Sheikha Latifa alongside Mary Robinson, former UN High Commissioner for Human Rights and former president of Ireland, and were purportedly taken on 15 December in Dubai.
What did Mary Robinson say?
Mrs Robinson told BBC Radio 4's Today programme that she had been invited by Princess Haya, wife of Dubai's ruler, to "help with a family dilemma".
"The dilemma was that Latifa is vulnerable, she's troubled. She made a video that she now regrets and she planned an escape, or what was part of a plan of escape," Mrs Robinson said.
"I had lunch with her. She's a very likeable young woman but clearly troubled, clearly needs the medical care that she is receiving."
Mrs Robinson said the princess was suffering from "a serious medical situation" and receiving psychiatric care, but did not give further details. She said her family didn't want her to "endure any more publicity".
What are the concerns?
The group Detained in Dubai legally represents two people who say they were attacked and abducted while trying to help the princess escape.
Ms Stirling said Mrs Robinson "had nothing to say" about the accusations Sheikha Latifa had made against her father.
"She said nothing about Latifa having planned her escape for nearly a decade, nor anything about her previous escape attempt," she said.
"She said nothing about the illegal raid of Latifa's boat in international waters, and the fact that she was screaming for asylum and begging to not be returned to the UAE. Mrs Robinson simply repeated again and again from the official Dubai statement that Latifa is in the 'loving care of her family' and that the whole issue is nothing more than a 'family matter'."
Another rights group, Guernica 37 International Justice Chambers, also said it was concerned by Mrs Robinson's comments.
"Mrs Robinson appears to have spent a couple of hours with Sheikha Latifa, and despite having no formal medical or psychiatric training, has somehow diagnosed her condition and concluded that she is receiving appropriate treatment. It is unclear on what basis Mrs Robinson considers herself qualified to do so," it said in a statement.