The head of the UN agency for Palestinian refugees, UNRWA, said Sunday that Israeli authorities had barred him from entering Gaza for a second time since the Israel-Hamas war started on October 7.

"Just this week, they have denied -- for the second time -- my entry to Gaza where I planned to be with our UNRWA colleagues including those on the front lines," Philippe Lazzarini wrote on X, formerly Twitter.

Lazzarini has been to Gaza four times since the war broke out including on March 17.

"The Israeli authorities continue to deny humanitarian access to the United Nations," he said on Sunday.

"Only in the past two weeks, we have recorded 10 incidents involving shooting at convoys, arrests of UN staff including bullying, stripping them naked, threats with arms & long delays at checkpoints forcing convoys to move during the dark or abort," Lazzarini said.

He also called for an "independent investigation" into rocket fire that led to the closure of a key Israel-Gaza aid crossing.

Hamas's armed wing, Ezzedine al-Qassam Brigades, claimed responsibility for the Sunday launch, saying militants had targeted Israeli troops in the area of Kerem Shalom crossing.