A missing Dubai princess has begged UK police to reinvestigate her sister's disappearance.
Emirati princess Latifa Al Maktoum claims to have been held in a "villa jail" for nearly three years.
Friends of the 35-year-old royal claim she is being imprisoned in the Kingdom by the powerful ruler of the emirate.
Last week Latifa's pals released video messages she secretly recorded from the villa, claiming they had become worried as she has gone silent.
Now, a letter from the princess obtained by the BBC shows she wrote to British authorities urging them to probe the 'kidnapping' of her old sister in Cambridge more than a decade ago.
In 2000, Princess Shamsa fled from her family's Longcross estate in a Range Rover.
Several weeks later, Shamsa was plucked from the streets of Cambridge and eventually returned to Dubai via private jet.
Latifa claims her father, Sheikh Mohammed bin Rashid Al Maktoum, has detained her ever since she attempted to flee the emirate in 2018.
Concerns for the young royal's welfare mounted in recent weeks after her worried friends released rare footage of the young royal describing her captivity to BBC Panorama.
Now a new letter from the princess has emerged in which she urges Cambridgeshire Police to reinvestigate the disappearance of her older sister Shamsa.
In the letter, Latifa claims Shamsa was also captured by her father.
Shamsa, now 38, has never been seen in public since she was abducted in Cambridge.
It is believed she was returned to the United Arab Emirates (UAE).
Latifa herself was then captured as she tried to flee Dubai in the Indian Ocean on a luxury yacht.
Cambridgeshire Police previously confirmed "aspects" of its 2001 investigation into her sister's disappearance - which found insufficient evidence to take any action - will be revisited, although the force insisted the investigation was no longer "active".
In Latifa's letter to the force about Shamsa, she wrote: "All I ask of you is to please give attention on her case because it could get her her freedom... your help and attention on her case could free her.
"She has strong links to England... she really loves England, all of her fondest memories are of her time there."
A Cambridgeshire Police spokesman said: "The review into the disappearance of Princess Shamsa continues.
"This is a very complex and serious matter and as such there are details of the case that it would be inappropriate to discuss publicly.
"We can confirm officers have recently received a letter, dated February 2018, in relation to this case which will be looked at as part of the ongoing review.
"In addition to this, we are also looking at the contents of the recent BBC Panorama documentary to identify whether it includes anything of significance to our case."
Footage filmed by Latifa of her life in the "villa jail" was broadcast this month.
It was described by Foreign Secretary Dominic Raab as "very distressing", and triggered worried responses around the globe.
David Haigh, a human rights lawyer representing Latifa, recently revealed she was taunted by her guards who gave her a stopwatch to count down her time in captivity,
He said he received the texts about the stopwatch last year.
He wants Latifa brought to the UK and claims she has been denied medical care in the villa where it is claimed she is being held.
“When I received the message about the timing device and the picture from Princess Latifa I was devastated, I knew it meant they planned to keep her there for a long time," Mr Haigh told media.
He added: “I also realised it was part of a cruel game, part of a three-year-long programme of torture."
Along with the video clip filmed last year from her bathroom and released last week, Latifa provided a drawing of the layout of her 'prison' to be shared with the world.
The exact location of the secret spot is not known - but it is widely believed to be just yards from Dubai’s tourist beaches popular with Brit celebrities.
He said her predicament showed she urgently needed the help of the outside world, as pressure grows on Britain to exercise its diplomatic relationship with Dubai.
But a family statement released through the UAE embassy in London downplayed allegations of mistreatment, and said she was being cared for at home.
It said: "She continues to improve and we are hopeful she will return to public life at the appropriate time."
