Archbishop Desmond Tutu will enter Gaza later this week to conduct a United Nations investigation into the killing of 19 Palestinian by Israeli shells in November 2006.
He is intending to visit the scene of the incident in which Israeli forces fired an artillery barrage into the Gazan town of Beit Hanoun.
The UN Human Rights Council set up the fact-finding mission in 2006, with Tutu charged with reporting back with his findings, but Tutu had been denied a visa for the last 18 months.
An Israeli official said that Tutu was welcome to come to Israel, but that cooperation would not be given for his investigation.
The Israeli army carried out its own investigation but found earlier this year that the incident was an accident, and held no individual to account for the deaths. Palestinian human rights campaigners were incensed by the finding.
Reports suggest that the first shell hit a crowded house, causing members of the Athamneh family to run out into an alley, where they were cut down by further shells. Almost all the dead were from the same family, with the youngest being an eight-month old girl.
Mr Tutu's trip represents a major showdown between the Jewish state and the UN Human Rights Council, which commissioned his inquiry weeks after the incident.
Israeli government sources have accused the council of being politicised and biased for ignoring other human rights violations such as Darfur, while repeatedly censuring Israel.
Despite this, Israel did not prevent Louise Arbour, the then-UN High Commissioner for Human Rights, from visiting the scene of the killings a few weeks after the incident.
Tutu is expected to be accompanied by British academic Christine Chinkin.
His report is to be delivered to this September's session of the human rights council.