1 / 11A prominent Saudi princess jailed without charges made a rare public appeal to the king and crown prince on Thursday for her release from a high-security prison, citing her 'deteriorating' health.2 / 11Princess Basmah bint Saud, a 56-year-old businesswoman and an outspoken royal family member, was detained in March last year just before she was due to travel to Switzerland for medical treatment, according to a source close to her family.3 / 11The public plea for her release is the latest sign of turmoil within the kingdom's secretive royal family following the detention last month of King Salman's brother and nephew in an apparent attempt to stamp out internal dissent.4 / 11The princess claimed she was 'thrown into prison' after being 'abducted without an explanation' along with one of her daughters.5 / 11She appealed to her uncle King Salman and her cousin - de facto ruler Crown Prince Mohammed bin Salman - for her release as she had 'done no wrong' and added that her health status was 'very critical'.6 / 11The princess did not specify her ailment but her letter comes as the kingdom grapples with the fast-spreading coronavirus pandemic.7 / 11The government has imposed round-the-clock curfew across much of the country to limit the spread of the virus. Saudi Arabia has reported 6,380 infections and 83 deaths from the disease so far.8 / 11Her public plea represents an unusually bold move by someone from the kingdom's sprawling royal family, comprising thousands of members, who typically refrain from publicly raising internal grievances. 9 / 11The government has yet to officially comment on the crackdown, which raised fears of government instability.10 / 11In 2013, Princess Basmah bint Saud bin Abdulaziz al Saud, as she is known in full, claimed she was being blackmailed out of £320,000 for criticising the the Saudi regime.11 / 11Since an interview with BBC Arabic last January in which she called for an end to the Saudi war in Yemen, Princess Basmah has made no major media appearances.