Karim Khan said in a statement published on X, formerly Twitter, that his office's investigation into events in Gaza is "being taken forward as a matter of the utmost urgency".

"I am deeply concerned by the reported bombardment and potential ground incursion by Israeli forces in Rafah," he said.

The ICC opened a probe in 2021 into Israel as well as Hamas and other armed Palestinian groups for possible war crimes in the Palestinian territories.

"All wars have rules and the laws applicable to armed conflict cannot be interpreted so as to render them hollow or devoid of meaning," he said.

"This has been my consistent message, including from Ramallah last year. Since that time, I have not seen any discernible change in conduct by Israel," he said.

Opening its doors in 2002, the ICC is the world's only independent court set up to probe the gravest offences including genocide, war crimes and crimes against humanity.

It is a "court of last resort" and only steps in if countries are unwilling or unable to investigate cases themselves.

"As I have repeatedly emphasised, those who do not comply with the law should not complain later when my Office takes action pursuant to its mandate," warned Khan.

"To all those involved: my Office is actively investigating any crimes allegedly committed. Those who are in breach of the law will be held accountable."