Geneva: The top United Nations human rights official is urging Israel to improve conditions for Palestinians in custody, especially the more than 1,000 whose hunger-strike entered its 40th day.

The strike followed a call by Marwan Barghouti, the most high-profile Palestinian held by Israel, for a protest against solitary confinement and an Israeli policy of detention without trial that has been applied to thousands of prisoners since the 1980s.

“I am especially alarmed by reports of punitive measures by the Israeli authorities against the hunger-strikers, including restricted access to lawyers and the denial of family visits,” Zeid Ra’ad Al Hussain, UN High Commissioner for Human Rights, said in a statement.

The right to consult a lawyer is a fundamental protection in international human rights law that should never be violated, Al Hussain said. He added that the health of hundreds of the hunger-strikers had “deteriorated significantly”.

While hunger strikes are not uncommon among the 6,500 Palestinians held in Israeli jails, the latest protest involves one of the largest number of prisoners.

It is likely to raise tensions between Israel and the Palestinians as the 50th anniversary of the Israeli occupation of the West Bank and East Jerusalem approaches in early June.

Al Hussain said his office had received reports that the Israel Prison Service had evacuated at least 60 hunger-striking Palestinian prisoners to hospitals because their medical condition had worsened. A further 592 had recently been moved for observation to infirmaries set up in the prisons, he said.

The International Committee of the Red Cross (ICRC), which visits Palestinian detainees, urged Israel early this month to allow family visits. Under international law, these “can only be limited for security reasons, on a case by case basis, but never for strictly punitive or disciplinary purposes”, it said.

ICRC added that “Israel detains Palestinians within its territory — but not within the occupied territory as required by the law of occupation”.