The UN expert on displacement said Friday she was "horrified" by Israel telling 1.1 million residents to evacuate the northern Gaza Strip, condemning the order as a crime against humanity.
Paula Gaviria Betancur, the United Nations' special rapporteur on the human rights of internally displaced persons, said it was inconceivable that Gazans could move across a war zone without devastating consequences.
Thousands of Palestinians fled to southern Gaza in search of refuge on Friday after Israel warned them to evacuate before an expected ground offensive against Hamas in retaliation for the deadliest attack in Israel's history.
"Forcible population transfers constitute a crime against humanity, and collective punishment is prohibited under international humanitarian law," Gaviria Betancur said in a statement. "We are horrified at the prospect of an additional one million Palestinians joining the over 423,000 people already forcibly driven from their homes by the violence over the past week."
"It is inconceivable that more than half of Gaza's population could traverse an active war zone, without devastating humanitarian consequences, particularly while deprived of essential supplies and basic services."
UN special rapporteurs are unpaid, independent figures mandated by the Human Rights Council. They do not speak for the UN but report their findings to it. Gaviria Betancur urged Israel to rescind the evacuation order immediately, saying those currently displaced had nowhere to go.
Meanwhile, the UN has also condemned Israel's order. UN chief Antonio Guterres appealed Friday for the protection of basic human rights as the Israel-Hamas conflict spiraled, stressing that "even wars have rules" and warning against using hostages as human shields.
"The situation in Gaza has reached a dangerous new low," Guterres said ahead of a Security Council meeting on the volatile situation.
"We need immediate humanitarian access throughout Gaza, so that we can get fuel, food and water to everyone in need," he said, adding that the blockaded enclave's health system was on the brink of collapse.
His call for the protection of civilians came as Israeli Prime Minister Benjamin Netanyahu said his country's fierce bombardment of Gaza was "just the beginning."