A Palestinian woman detained by Israel who has been on hunger strike for the past month is at "immediate risk of death", a medical rights group says.
Hana Shalabi, 30, needs to be transferred to hospital immediately, according to the Physicians for Human Rights (PHR)-Israel group.
Ms Shalabi is protesting against being held without charge under a system called "administrative detention."
Israel uses the measure against those it deems a security risk.
Ms Shalabi has lost 14kg (31lbs), her muscles are wasting and she is in excruciating pain, Ran Cohen of PHR-Israel told the Associated Press news agency.
PHR-Israel says it and other human rights groups "share fears regarding the adequacy and timeliness of the medical care available [to Ms Shalabi], especially given the growing concern about her rapidly deteriorating condition".
For the time being, Ms Shalabi is being monitored at a prison clinic, an Israel Prison Service spokesperson told AP.
Ms Shalabi is reportedly a supporter of the militant group Islamic Jihad, which Israel has designated a terrorist organisation.
Ms Shalabi was one of the Palestinian prisoners freed from Israeli jails as part of the deal to free kidnapped Israeli soldier Gilad Shalit deal last October, but was detained again in February.
Prison authorities say 20 other Palestinian detainees have launched hunger strikes in support of Ms Shalabi in the past two weeks, AP reports.
Last month another Palestinian prisoner, Khader Adnan, ended a 66-day hunger strike after reaching a deal with the Israeli authorities that will see him released in April.
Adnan, who is widely believed to be a leader of Islamic Jihad, is also being held under "administrative detention".