According to Alanouf AlFayez, 57, her billionaire ex-husband, King Abdullah, has imprisoned her adult daughters in a royal palace for 13 years.
AlFayez has lived in London since her husband divorced her in 2003, but her daughters, who remain trapped in Saudi Arabia, are being held against their will.
Their mother says they are now even being prevented from leaving the house to buy themselves supplies of food and medicine.
Two of the daughters, Saha and Kawaher, emailed the Sunday Times to tell them that they were being kept in a closed off house, under surveillance of the King's brothers, and have had their passports and IDs removed.
'We are under house arrest,' they wrote. 'With little food left for ourself and pets.'
The email continued:
'On their orders, they have been literally starving us since last Wednesday. We are now living on one meal a day, leaving the little remaining meat for our pets and supping little water in this heat, to save up. Our energy is quite low and we are trying our best to survive.'
One of the princesses is suffering from extreme anorexia and mental problems.
Their father, Kind Abdullah, has ruled the oil-rich nation of Saudi Arabia since 2005. He is one of the wealthiest men in the world, being estimated as worth £11 billion.
He has 38 children by a number of different wives .
Saudi Arabian law forbids women and girls from travelling, conducting official business, or undergoing certain medical procedures without the permission of male guardians. It is also illegal for women to drive.
AlFayez has called on Obama to demand the release of her daughters as he visits the country this month.
One of the imprisoned daughters Sahar said that the ill treatment of her and her sisters began when they started to speak up about the 'brutal and oppressive' regime endured by most Saudi citizens.