The Israeli military says it has launched the first stages of a new major offensive in Gaza, in a development that comes on the same day that US President Donald Trump concluded his visit to the region without securing a ceasefire deal.

Israel said Saturday it had launched a major operation in the Gaza Strip to pressure Hamas to release remaining hostages.

The withering Israeli aerial campaign appeared to presage the ground operation Prime Minister Benjamin Netanyahu has vowed to launch if no ceasefire and hostage deal were struck by the time Trump returned to the U.