Israel's military on Friday called for all civilians of Gaza City — more than 1 million people — to relocate south within 24 hours, as it amassed tanks near the Gaza Strip ahead of an expected ground invasion.

"Now is a time for war," Defense Minister Yoav Gallant said on Thursday as Israeli warplanes continued pounding Gaza in retaliation for the weekend attacks by Hamas militants that killed more than 1,300 Israelis, mostly civilians.

The Israeli military said it would operate "significantly" in Gaza City in the coming days and civilians would only be able to return when another announcement was made.