GENEVA

The UN's Palestine refugee agency UNRWA warned Friday that Gaza is fast becoming a "hell hole" amid intensifying violence, urging protection of civilians across the blockaded enclave.

Calling Israel's order for the evacuation of more than a million Palestinians from northern Gaza within the next 24 hours "horrendous," UNRWA Commissioner-General Philippe Lazzarini said in a statement: "This will only lead to unprecedented levels of misery and further push people in Gaza into abyss."

The Israeli army on Friday ordered all residents of northern Gaza to evacuate their homes and head to the south.

Lazzarini said over 423,000 people had already been displaced since Saturday, and 270,000 had taken refuge in UNRWA shelters.

"The scale and speed of the unfolding humanitarian crisis is bone-chilling," he said. "Gaza is fast becoming a hell hole and is on the brink of collapse."

Stressing that UNRWA is "struggling to fulfil its mandate" as more than two million people in Gaza are caught up in the conflict, he urged: "There is no exception, all parties must uphold the laws of war; humanitarian assistance must be provided at all times to civilians."

He also called on all parties and those with influence over them to put an end to this tragedy and provide immediate and unconditional humanitarian access and protection to the civilians, among them far too many women and children.

"The time for humanity to prevail is now," the official said.

In a dramatic escalation of Middle East tensions, Israeli forces launched a sustained and forceful military campaign against the Gaza Strip, a response to a military offensive by the Palestinian resistance group Hamas in Israeli territories.

The conflict began last Saturday when Hamas initiated Operation Al-Aqsa Flood against Israel, a multi-pronged surprise attack including a barrage of rocket launches and infiltrations into Israel via land, sea and air.

Hamas said the operation was in retaliation for the storming of the Al-Aqsa Mosque in occupied East Jerusalem and Israeli settlers' growing violence against Palestinians.

The Israeli military then launched Operation Swords of Iron against Hamas targets within the Gaza Strip.

Israel's response has extended into cutting water and electricity supplies to Gaza, further worsening the living conditions in an area that has reeled under a crippling siege since 2007.