The UN Human Rights Office has said it is following the situation in Israel and Gaza with "deepening horror," and urged all parties involved in the conflict to respect international humanitarian law.

"More than 2,700 people, including civilians, have already been killed in both Israel and Gaza. We urge Palestinian armed groups to halt the use of inherently indiscriminate projectiles, which violate international humanitarian law, as well as attacks directed against civilians. And we urge Israel to ensure full respect for international humanitarian and human rights law in any and all military operations," spokesperson for the UN High Commissioner for Human Rights Ravina Shamdasani said Friday.

Shamdasani said that UN High Commissioner for Human Rights Volker Türk urges all States to "insist upon and assist the parties to the conflict in immediately implementing a humanitarian corridor to ensure safe and unimpeded access to humanitarian aid."

"We should not look back and regret that we did not do everything in our power to avoid a disaster," she added.

Israel's military has warned all civilians in the north of Gaza to evacuate "southwards."

"This order is affecting more than a million Palestinians, including children, older and sick people, forcing them to relocate with little or no transport and with scant guarantees for their safety, amidst continuing hostilities.

"We echo the Secretary-General’s Spokesperson’s call for this to be rescinded, avoiding a calamitous situation," Shamdasani said.