Riyadh: A Saudi rights group on Monday called on King Abdullah Bin Abdul Aziz to intervene to free a woman who was sent to prison for disobeying her father.

Human Rights First Society (HRFS) accused the government of "outrageous illegal detention" in the case of Samar Badawi, who was thrown in prison six months ago without official charge or trial by a Jeddah judge who said she was disobedient to her father and guardian.

The case is another instance of abuse of the "mahram" or guardian system, HRFS said.

Under the system, a Saudi woman must have the permission of her official male guardian - a father, husband, brother or son - for matters such as travel and work.

Women in the kingdom are also prohibited from driving.

Samar, a divorced mother of 32, had asked the court that her father be removed as her legal guardian, saying he had mistreated her since childhood, according to a website advocating her release.

The judge rejected her request and ordered her taken to prison.

In a statement, HRFS called on King Abdullah "to intervene for the immediate and unconditional release of Samar Mohammad Badawi and for total abolition of the guardianship [mahram] system in Saudi life and laws."

"Short of total unconditional legal status and identity for Saudi women, all reforms pertaining to women will be cosmetic and totally ineffective," it said.