A Palestinian hunger striker held by Israel is in critical condition and could die at any moment from a range of maladies, a doctor who has examined him said Monday, after the country’s Supreme Court rejected an appeal to release the man.

Khalil Awadeh, 40, has been on a hunger strike since March to protest his so-called administrative detention, an Israeli policy of holding Palestinians for alleged involvement in militant activity. Detainees can be held without charge or trial for months or years at a time, without seeing the purported evidence against them. Israel describes the policy as a necessary security measure, while critics say it is a violation of due process.

Awawdeh’s family says he has been on the hunger strike for 170 days, subsisting only on water. Photos of Awawdeh taken by his lawyer on Friday showed him emaciated and lying in a hospital bed.

Dr. Lina Qasem-Hassan, a doctor with Physicians for Human Rights who visited Awadeh earlier this month, said he was extremely thin and suffering from malnutrition.

She said there are signs of neurological damage, with symptoms like memory loss, an inability to concentrate, involuntary eye movement and a near loss in vision. She said there was a risk of heart failure or kidney failure at any time.

“There is no doubt there is a risk for his life,” she said.

His lawyer, Ahlam Haddad, appealed last week to the Supreme Court to release him due to his failing health. But on Sunday, the court rejected the appeal.

In its ruling, the court said it had examined classified security information about Awawdeh and determined there was “solid and strong justification for the decision of administrative detention.”

Haddad said she would file another request for his release as soon as his condition worsens. “This is the equation, a difficult equation,” she said.

Israel’s Shin Bet security agency did not respond to a message seeking comment.

The Israeli military arrested Awawdeh last December, claiming he was an operative for the Palestinian Islamic Jihad militant group — an allegation that his lawyer has dismissed.

Awawdeh is one of several Palestinian prisoners who have gone on prolonged hunger strikes in recent years to protest their administrative detentions. Many continued to suffer permanent health problems after their release.

Israel says administrative detentions help keep dangerous militants off the streets and allow the government to hold suspects without divulging sensitive intelligence or evidence against the suspects. Critics say it denies prisoners due process and is aimed at quashing opposition to Israel’s 55-year occupation of territories the Palestinians seek for a future state.

Israel is currently holding some 4,400 Palestinian prisoners, including militants who have carried out deadly attacks, as well as people arrested at protests or for throwing stones.

Around 670 Palestinians are currently being held in administrative detention, a number that has jumped since March as Israel began near-nightly arrest raids in the occupied West Bank following a series of deadly attacks against Israelis.

Awawdeh’s family says he has not eaten food since March, though he took some vitamin supplements over two weeks in June when he thought his case was being resolved.