AFP journalists on the ground early Tuesday reported fresh Israeli strikes overnight in the southern Gaza border city, where an Israeli attack targeting two senior “Hamas” members on Sunday night sparked a fire that ripped through a displacement centre, killing 45, according to Gaza health officials.
The attack prompted a wave of international condemnation, with Palestinians and many Arab countries calling it a "massacre". Israel said it was looking into the "tragic accident".
"There is no safe place in Gaza. This horror must stop," UN Secretary-General Antonio Guterres posted on social media.
UN humanitarian chief Martin Griffiths pointed to the widespread warnings of civilian deaths that circulated ahead of Israel's incursion into Rafah, saying in a statement: "We've seen the consequences in last night's utterly unacceptable attack."
"To call it 'a mistake' is a message that means nothing for those killed, those grieving, and those trying to save lives," he added.
Diplomats said the UN Security Council would convene Tuesday for an emergency session called by Algeria to discuss the attack.
The EU's foreign policy chief said he was "horrified by news" of the strike, while French President Emmanuel Macron said he was "outraged", and a US National Security Council spokesperson said Israel "must take every precaution possible to protect civilians".
The Israeli military said it was launching a probe.