A UN team investigating possible war crimes in Gaza, led by Richard Goldstone, has arrived in the Strip on a week-long fact finding mission, BBC reported.
The four-member team entered from Egypt after Israel failed to grant visas, despite repeated requests by the UN.
The UN wants to investigate whether Israel and Hamas committed war crimes during Israel's three-week operation in Gaza in December and January.
Israel accuses the UN branch carrying out the mission of bias against it.
The UN Human Rights Council has been accused of singling out Israel unfairly, and is viewed by some as having less credibility than other parts of the United Nations.
But correspondents say the selection of Mr Goldstone, a respected South African war crimes prosecutor who is also Jewish, as head of the inquiry has given it greater clout.
"They have been instructed to prove that Israel is guilty and we will not collaborate with such a masquerade," foreign ministry spokesman Yigal Palmor told AP news agency.
Public hearings
The team plans to meet "all concerned parties", including non-governmental organisations, UN agencies and victims and witnesses of alleged violations of international humanitarian law, its office said in a statement.
Mr Goldstone has previously said his team had hoped to visit southern Israeli towns which have suffered Palestinian rocket fire , before entering Gaza from Israel, but Israel has shown no sign of allowing access.
Israel was initially angered that the team was tasked only with investigating alleged Israeli violations, but after Mr Goldstone was appointed, its mandate was widened to cover the activities of Palestinian militants too.