The death toll in the shelling of a family compound in Gaza rose to 30, the United Nations said in a report issued on Friday, as relief workers continued to comb through wreckage they had been denied access to for days after the attack.

The episode has ignited intense international criticism of the Israeli military for its failure to allow relief workers to reach the scene in a timely manner. On Friday, the United Nations High Commissioner for Human Rights, Navanethem Pillay, also pointed to the deaths in the family compound as cause for an independent investigation into possible war crimes by Israeli forces in Gaza.

"Incidents such as this must be investigated because they display elements of what could constitute war crimes," she told Reuters.

Initial reports on Monday said 11 members of the extended Samouni family had been killed and 26 wounded, according to witnesses and hospital officials, with five children aged 4 and under among the dead.