Israel has told 1.1 million people in northern Gaza to leave for the south of the territory and thousands were still using safe routes designated by Israel to seek safety on Sunday.

Israel has faced pressure from the United Nations and its allies to hold back on any invasion until civilians have been given every chance to leave. The military has not said when the safe passage windows will close.

Military spokesmen Lieutenant Richard Hecht and Daniel Hagari told separate briefings on Sunday that "a political decision" will set off any action against Hamas after its October 7 attacks that left at least 1,300 dead in Israel.

"We will be holding discussions with our political leadership," Hecht told one briefing.

Israel has massed tens of thousands of troops around Gaza and officials say that all necessary military supplies have been carried out. Thousands of air raids have been staged in Gaza since the October 7 attacks, claiming more than 2,300 lives in the densely populated territory.

Prime Minister Benjamin Netanyahu told troops near the Gaza border on Saturday that "more is coming". But he did not say when any ground operation would start. Netanyahu has been holding regular security meetings with key ministers and military leaders.

Defence Minister Yoav Gallant discussed the evacuation of Gaza civilians and "humanitarian issues" in talks with US senators today, his department said.

Gallant stressed "Israel's military power and our determination to destroy the enemy".

Military spokesmen have told reporters that any invasion would aim to eradicate Hamas' militant network and leadership so that it cannot stage more attacks.

The Israeli military has particularly singled out Yahya Sinwar, the chief of Hamas in Gaza they blame for the October 7 attacks. "That man is in our sights," Hecht said on Saturday. "He is a dead man walking and we will get to that man."