Israel’s government has shown US Secretary of State Antony Blinken and NATO defence ministers graphic images of dead children and civilians, saying they were killed by Palestinian group Hamas as it builds support for its response.

Prime Minister Benjamin Netanyahu’s office on Thursday (local time) also released on social media a picture of a dead infant in a pool of blood and the charred body of a child, part of an apparent effort to stoke global anger against the Gaza militants over Saturday’s attack.

Blinken, who flew into Tel Aviv earlier on Thursday, said he was shown photographs and videos of a baby riddled with bullets, soldiers beheaded and young people burned alive in their cars or hideaways.

“It’s simply depravity in the worst imaginable way,” Blinken said.

“Images are worth a thousand words. These images may be worth a million.”

Netanyahu has vowed to annihilate Hamas following its deadly assault on unsuspecting Israeli communities on Saturday, which killed more than 1300 people, the deadliest attack on Israel since it was founded in 1948.

The Israeli airforce has launched intense bombing raids on Gaza over the past five days and is massing tens of thousands of troops along the border ahead of a possible ground invasion.

Gaza authorities said more than 1400 Palestinians, mainly civilians, including children, have already been killed and more than 6000 wounded. A land invasion in the densely populated territory could send the toll much higher.

In a message on X, Netanyahu’s office released what it said were “horrifying photos of babies murdered and burned by the Hamas monsters”.

It added: “Hamas is inhuman. Hamas is ISIS,” comparing the Palestinian group to the Islamic State, which was notorious for its brutality and gory execution videos.

The images of the dead infants were included in the video played to NATO. It was not released to the public, but was later seen by Reuters in Jerusalem. Reuters could not independently verify the material.

“They were horrific pictures of the attacks and the victims of the attacks,” NATO Secretary General Jens Stoltenberg said, saying it “confirmed the brutality of the attacks”.

The White House said it had no reason to doubt the authenticity of the images.

Hamas has denied its militants harmed civilians, accusing Israel and the West of spreading false reports to incite violence against Palestinians.

The video shown to NATO, apparently taken from a mix of social media published by Hamas and unidentified phone videos, showed the bodies of scores of dead civilians, as well as the body of an Israeli soldier in uniform with his head missing.

There were no images to suggest militants had beheaded babies – a particularly explosive accusation that first emerged in Israel’s media and was initially confirmed by Israeli officials.

US President Joe Biden had suggested on Wednesday he had seen images of children beheaded by militants. The White House later clarified that US officials had seen no evidence of that.

Netanyahu has not repeated a claim by his office earlier this week that Hamas had indeed cut off the heads of children, nor did Gallant repeat that accusation to NATO ministers.

But medics, international human rights organisations and journalists have documented that militants killed women, children and the elderly as well as young men and soldiers in their rampage.

Foreign reporters shown sites targeted by Hamas, witnessed ruins of burnt-out houses and streets scattered with dead residents and militants.

NATO officials said they did not expect the alliance to be directly involved in the conflict. But multiple NATO states, above all the United States, have offered Israel military aid.

US Defence Secretary Lloyd Austin said after the NATO meeting on Thursday that Washington was not placing any conditions on its security assistance to Israel and expected Israel’s professional military to “do the right things”.