Twenty-one-year-old Amina Al-Jeffery was born in Swansea but then taken to Saudi Arabia, aged 16, as her father "disapproved of her relationships and conduct".
She has since been held as a prisoner at her father's home in Jeddah, starved of food and water and physically abused, because he disapproved of her "kissing a guy".
The woman, who has dual Saudi and UK citizenship, said there had been a "practice of locking her in her room".
She also said that a younger sister had been told she was an "evil girl".
Ms Al-Jeffery further added that "metal bars are no longer in her room" but "she is still locked up in the house" and "not allowed to use the phone or internet".
She spoke of being "prevented from going to the bathroom" and "forced to urinate in a cup".
Lawyers representing Miss Al-Jeffery say they fear for her safety and have taken the legal action in London in a bid to protect her.
The judge said yesterday that issues raised were 'important and difficult', and said the 'right thing' might be to order that Miss Al-Jeffery was taken to the British Consulate.
The hearing continues and is expected to end today.