Israel's government has barred a UN human rights delegation from visiting the Palestinian areas on a fact-finding mission, the leader of the group said on Tuesday.

"Israeli authorities did not allow us to visit the Palestinian territories," said Prasad Kariyawasam, head of the UN panel, adding that "no reasons were given by Israel because they do not recognize our mandate." 

Kariyawasam told a news conference in the Jordanian capital, Amman, that despite the ban by the Jewish state, the committee has interviewed Palestinians from the Gaza Strip, and the Occupied West Bank, as well as Occupied East Jerusalem.

Some were interviewed by telephone as several witnesses were prevented from traveling to Amman or Cairo, he said.

"The international community has a moral and legal obligation to ensure that all international human rights and humanitarian law standards are fully implement at all times," Kariyawasam said.

The three-member panel, which has already visited Egypt and planned to go to Syria later on Tuesday, expressed serious concern about the conditions of Palestinians in the occupied areas. It warned against "the deteriorating human rights and humanitarian situation in the occupied Palestinian territory, the grave situation in the Gaza strip, the impact of the separation wall on the human rights of Palestinian people, and the continuing settlements policy," according to Kariyawasam.

The UN and other international organizations say Israeli-imposed sanctions on Gaza, which has been ruled by the Islamist Hamas movement since last year, have increased poverty and destroyed the economy in the densely populated area.

"Such policies and practices affecting Palestinian people are a serious threat to self-determination of the Palestinian people and must be halted immediately," Kariyawasam said.

The panel - the UN Special Committee to Investigate Israeli Practices Affecting the Human Rights of the Palestinian People and Other Arabs of the Occupied Territories - will submit a report to the UN General Assembly later this year.