Israel's ultimatum to more than a million Gazans giving them 24 hours to evacuate to the south of the coastal enclave was condemned Friday by countries and organisations around the world.

The United Nations said it had been informed of the order shortly before midnight but as thousands of people streamed southwards in cars and on foot, the Israeli army admitted that the evacuation would "take time".

Herewith the main reactions so far:

United States 

The White House said the evacuation demand was a "tall order".

"It's already a combat zone. So I don't think anybody's underestimating the challenge here of effecting that evacuation," National Security Council spokesman John Kirby told CNN. 

Secretary of State Antony Blinken was working with Israel "on the need to establish some safe areas where civilians could relocate, be safe from Israel's legitimate security operations," a US official said.

United Nations 

The UN described such a population transfer in so short a timescale as "impossible" and urged Israel to rescind the order. 

It announced it was relocating its agency for Palestinian refugees and foreign staff to southern Gaza. 

Red Cross

The International Committee of the Red Cross said Gazans had "nowhere safe to go" and it was "impossible" for them to know which areas "will next face attack".

With a military siege in place, humanitarian organisations "will not be able to assist such a massive displacement of people in Gaza".

Turkey

Turkey called the evacuation demand "unacceptable".

"Forcing the 2.5 million residents of Gaza, who have been subject to indiscriminate air strikes for days and deprived of electricity, water and food, to migrate in an extremely limited area is a flagrant violation of international law and is inhumane," the foreign ministry said in a statement.

World Health Organisation

Palestinian officials told the WHO that moving vulnerable hospital patients to the southern Gaza Strip was "impossible".

Hospitals in the south of Gaza were already "overflowing", WHO spokesman Tarik Jasarevic said in Geneva. "With ongoing airstrikes, civilians have no safe place left to go".

Palestinian Authority

Palestinian president Mahmud Abbas warned of a "second Nakba", a reference to some 760,000 Palestinians who fled or were expelled from their homes during the 1948 war that coincided with Israel's creation.

Abbas said he "completely rejects the displacement of our people from the Gaza Strip, because it will be tantamount to a second Nakba for our people".

Arab League

The Cairo-based Arab League condemned a "forced transfer" that constitutes "a crime".

Leader Ahmed Abul Gheit accused Israel of carrying out "an atrocious act of revenge... punishing helpless civilians in Gaza," rather than a "planned or studied military operation" on uprooting Hamas militants over their deadly attacks on Israeli soil.

Egypt

Egypt's President Abdel Fattah al-Sisi urged Gazans to "stay steadfast and remain on their land", amid calls for Cairo to allow safe passage through its Rafah crossing for civilians stuck in Gaza.

US officials said they were in talks with Egypt to open the Rafah crossing to foreign nationals who want to flee.

Germany

At a news conference during a visit to Jerusalem, Germany's Foreign Minister Annalena Baerbock condemned Hamas for taking "the entire population of Gaza hostage". She accused Hamas of "barricading itself behind more innocent people and is using them as a shield".

Russia

Russia's President Vladimir Putin compared Israel's siege of Gaza to the Nazis' World War II blockade of Leningrad.

"Various scenarios are emerging, including the possibility of military and non-military measures being taken against the Gaza Strip comparable to the siege of Leningrad during World War II," Putin told journalists in Kyrgyzstan.

"We understand what that entails. In my opinion, this is unacceptable. More than two million people live there," he added.