Israel has demanded that the United Nations reject a report which blames Israeli military measures for hunger among Palestinians.
Israel's ambassador to the UN in Geneva accused the report's author, a UN special rapporteur on the right to food, of abusing his office, saying that he had not declared membership of a non-governmental organisation (NGO) critical of Israeli policy.
In his report, drawn up after a visit in the summer authorised by Israel, Swiss professor Jean Ziegler warned that Israeli security measures were creating hunger and malnutrition in Palestinian areas.
"The occupied Palestinian territories is on the verge of humanitarian catastrophe as a result of extremely harsh military measures," he said.
In a letter to UN Commission on Human Rights, Ambassador Yaakov Levy said Ziegler had told French television station LCI he was a member of the Alternative Information Centre, a Tel Aviv-based NGO, which the envoy called "politically biased".
"The fact that Mr Ziegler is a member of such an organisation is in contradiction to the qualities of independence and impartiality necessary for the position of special rapporteur," Levy wrote in the letter, a copy of which was sent to news agencies.
"I expect that the relevant authorities will ask Mr Ziegler to withdraw his report and that the Commission will deem his report unfit for presentation to the Commission ... as well as for distribution as a UN document," he said.
"I obey the rules. I am not withdrawing the report"
UN special rapporteur on the right to food
Ziegler had "abused" his position by giving press interviews criticising Israel, the ambassador added.
But Ziegler, a former socialist party member of the Swiss parliament, told the Reuters news agency that special investigators were allowed to be members of NGOs provided these were recognised by the UN and based in democratic countries.
"I obey the rules. I am not withdrawing the report," he said, adding that the Alternative Information Centre was one of Israel's oldest NGOs and was committed to non-violence.
Ziegler said he was also a member of numerous other NGOs, including Amnesty International. Commission chairwoman Najat Al-Hajjaji could not immediately be contacted for comment.