UN envoy Robert Serry
UN envoy Robert SerryFlash 90

The United Nations' Gaza envoy has expressed his "outrage" at an incident in which Palestinian protesters attempted to storm UN headquarters in Gaza, accusing Hamas of turning a blind eye.

"During a pre-announced demonstration, of which Hamas was well aware, a number of protestors climbed the perimeter wall and entered the compound causing damage to United Nations premises and property," Robert Serry said in a statement quoted by the Bethlehem-based Maan News Agency.

Expressing his "deep concern" over Hamas authorities' inaction, Serry issued a rare scathing criticism of the Islamist terrorist group which runs Gaza.

"Pending a full transfer of security responsibilities to the legitimate Palestinian Authority, we continue to hold Hamas fully responsible for the security and safety of all United Nations personnel and operations in Gaza," he continued, and added he would be issuing an urgent revue of the UN's operations in Gaza as a result of Wednesday's incident.

The riot erupted yesterday, as hundreds of protesters tried to storm the headquarters of the United Nations Relief and Works Agency (UNRWA), after the UN announced it lacked funds to rebuild the enclave from the damage wrought by Hamas's most recent war against Israel.

As well as the UN, protesters chanted slogans against the Palestinian Authority, Israel and even Robert Serry himself.

Such an open protest would not have been possible without the consent - passive or direct - of Hamas authorities.

In a statement Tuesday, UNRWA claimed the lack of funds was due to the failure of states to make good on their promises of aid.

"$5.4 billion was pledged at the Cairo (aid) conference last October and virtually none of it has reached Gaza. This is distressing and unacceptable. It is unclear why this funding has not been forthcoming," the agency said in a statement.

The reconstruction has barely begun, not only because world nations have not delivered, but also because construction materials allowed in by Israel have been diverted by Hamas to rebuild terror tunnels into Israel meant to attack civilians, leading Israel to limit the transfers.

Earlier this month Hamas threatened the international community, demanding that it pay to rebuild Hamas's stronghold of Gaza, or else face the region "becoming" a hotbed for extremism and terrorism.