JERUSALEM/GAZA/TEL AVIV: Israel's government showed U.S. Secretary of State Antony Blinken and NATO defence ministers graphic images of dead children and civilians on Thursday, saying they were killed by Palestinian group Hamas as it builds support for its response.

Prime Minister Benjamin Netanyahu's office 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 Hamas over Saturday's attack.

Blinken, who flew into Tel Aviv earlier on Thursday, told reporters 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 told a news briefing. "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 1,300 people, the deadliest attack by the Palestinian group since Israel 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.

In Israel, Lieutenant General Herzi Halevi, the country's military chief said on Thursday, "Now is the time for war."

Gaza authorities said more than 1,400 Palestinians, mainly civilians, including children, have already been killed and more than 6,000 wounded. A land invasion in the densely populated territory could send the toll much higher.

Israeli Defence Minister Yoav Gallant played a video to his counterparts at NATO's Brussels headquarters that he said showed horrific scenes from the surprise Hamas attack.

"Children were tied up and shot. Yes, I repeat, children, tied up and shot," he told fellow ministers by video link according to a text of his address sent to Reuters.

'HORRIFIC PICTURES'

In a message on the social media site '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 told reporters, saying it "confirmed the brutality of the attacks".

In quotes published by Hamas, deputy Hamas chief, Saleh Al-Arouri, said: "The plan was to target the army's Gaza team and fight occupation soldiers only."

But the White House said it had no reason to doubt the authenticity of the images. Authenticated video footage and witness accounts paint a picture of a Hamas ground assault and rocket barrages that ripped communities apart.

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 the group had beheaded babies -- a particularly explosive accusation that first emerged in Israel's media and initially confirmed by Israeli officials.

U.S. President Joseph Biden had suggested on Wednesday that he had seen images of children beheaded by the group. The White House later clarified that U.S. officials had not seen any evidence of this.

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 Hamas 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.

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.

U.S. Defense 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".