Ten Palestinian hunger strikers held at an Israeli prison have now been moved to hospital because of their deteriorating health, the Palestinian envoy to the United Nations said Friday.

Prisoners Bilal Diab and Thaer Halahla, on hunger strike for more than 65 days, are now in "grave condition," Palestinian representative Riyad Mansour said in a letter to the UN Security Council.

At least 1,550 Palestinian prisoners are now on hunger strike in Israeli jails protesting their detention.

Mansour said 10 prisoners at the Ramle prison have now been moved to hospital and the lives of "several" who have been on hunger strike for between 59 and 67 days were at risk.

Diab and Halahla "are suffering life-threatening conditions, including severe weight loss, nerve damage, dehydration, decreased muscle tone and low blood pressure," added the envoy. Both prisoners have been on hunger strike since February 29.

The two men appeared before Israel's Supreme Court on Thursday to appeal their detention without charge. Diab fainted during his hearing, his lawyer said.

All the hunger strikers are "protesting Israel's malicious treatment of Palestinian civilians" held in prisons, including more than 300 held without charge under "administrative detention," said Mansour.

Palestinian envoys have sought in recent weeks and months to step up pressure on Israel over the issue of prisoners and new settlements in the occupied Palestinian territories.