The warning came as Israel stepped up the renewed assault it launched on Tuesday, shattering the relative calm that had reigned in the war-battered territory since a January 19 ceasefire.

Gaza's civil defence agency said Israeli strikes killed 11 people on Friday -- three in pre-dawn strikes and eight more during the daytime.

On Thursday, it had reported a death toll of 504 since the bombardment resumed, one of the highest since the war began more than 17 months ago with Hamas's attack on Israel.

"I ordered (the army) to seize more territory in Gaza... The more Hamas refuses to free the hostages, the more territory it will lose, which will be annexed by Israel," Katz said in a statement.

Should Hamas not comply, Katz also threatened "to expand buffer zones around Gaza to protect Israeli civilian population areas and soldiers by implementing a permanent Israeli occupation of the area".

The military urged residents of the Al-Salatin, Al-Karama and Al-Awda areas of southern Gaza to evacuate their homes on Friday ahead of a threatened strike.

"For your safety, head south toward the known shelters immediately," Israeli military spokesman Avichay Adraee said in a post on X.

AFP images from northern Gaza showed donkey carts piled high with belongings as residents fled their homes along rubble-strewn roads.

- 'Pressure points' -

Israel resumed intensive bombing of Gaza on Tuesday, citing deadlock in indirect negotiations on next steps in the truce after its first stage expired early this month.

Its resumption of large-scale military operations was coordinated with US President Donald Trump's administration but drew widespread condemnation.

Turkey condemned what it said was a "deliberate" attack by Israel on a Turkish-built hospital in Gaza. "We strongly condemn the destruction by Israel of the Turkish-Palestinian Friendship Hospital," its foreign ministry said.

Russian President Vladimir Putin expressed "concern" over the fresh Israeli assault in a telephone call Friday with the ruler of Qatar, one of the mediators of the January ceasefire.

Israeli President Isaac Herzog expressed concern about the government's actions in a video statement on Thursday, saying it was "unthinkable to resume fighting while still pursuing the sacred mission of bringing our hostages home".

Thousands of protesters have rallied in Jerusalem in recent days, accusing Prime Minister Benjamin Netanyahu of resuming military operations without regard for the safety of the hostages.

Of the 251 hostages seized during Hamas's October 7, 2023 attack, 58 are still held by Gaza militants, including 34 the Israeli military says are dead.

The Israeli military said on Thursday that it had closed off the territory's main north-south route as it expanded the ground operations which resumed on Wednesday.

- Projectiles from Gaza -

Israel's military said it intercepted two projectiles fired from northern Gaza on Friday, after air raid sirens sounded in the southern city of Ashkelon.

On Thursday, sirens went off in central Israel as Hamas said it fired rockets at Tel Aviv in its first military reponse to Israel's resumed offensive. The military said it intercepted one rocket, while two hit an uninhabited area.

"We will intensify the fight with aerial, naval and ground shelling as well as by expanding the ground operation until hostages are freed and Hamas is defeated, using all military and civilian pressure points," Katz said.

He said these included implementing Trump's proposal for the United States to redevelop Gaza as a Mediterranean resort after the relocation of its Palestinian inhabitants to other Arab countries.

When asked if Trump was trying to get a Gaza ceasefire back on track Thursday, White House Press Secretary Karoline Leavitt told reporters that the president "fully supports" Israel's renewed Gaza operations.

Israel rejected negotiations for a promised second stage of the truce, calling instead for the return of all of its remaining hostages under an extended first stage.

That would have meant delaying talks on a lasting ceasefire, and was rejected by Hamas as an attempt to renegotiate the original deal.