PARIS, France -- Israel is organising showings for media around the world of a film depicting Hamas' October 7 massacre of hundreds of Israeli citizens, assembling raw footage sourced from victims and perpetrators alike.

The harrowing 44-minute montage has already been shown at the UN in New York and Geneva, in Washington, Berlin, Brussels, Madrid and Chilean capital Santiago, with a further screening in Paris for the press on Tuesday.

"We've screened this film in about 30 countries. We think it's important that people... know what happened on October 7," said Hen Feder, spokesman for the Israeli embassy in France.

The shock attack by the Palestinian militant group on Israel on October 7 left 1,400 dead and some 240 taken hostage, in the worst attack on Israel since its 1948 founding.

Israel has vowed to destroy the Islamist militants, launching a campaign in the Gaza Strip that has killed more than 10,300, mostly civilians, according to the Palestinian territory's Hamas-run health ministry.

The deeply shocking film screened by Israel is not available to the general public. In Paris it was seen by around 50 invited journalists, while it has been seen by a mixed audience of journalists and diplomats in other cities.

- 'Get message through' -

While some voices, particularly in the Arab world, have made baseless claims of doubt on whether civilians were really massacred by Hamas, Israel "is trying to get the message across through the media" that the killings did indeed happen, Feder added.

One sobbing guest left the Paris showing before the film ended, while others sat silently through the session.

The screen showed a series of bloodied, burned and tormented bodies of men, women and children.

Lying in bushes, living rooms and bathrooms, many no longer resembled human forms.

One clip showed a metres-long trail of blood across brightly-coloured floor tiles.

The Israeli government says it has gathered hundreds of hours of footage of the Hamas attack.

The images are compiled from bodycam and smartphone footage shot by slain or captured Hamas fighters, the militant group's social media posts and the phones of victims and first responders, Israeli diplomats said.

Among them are clips of armed men killing civilians, including in kibbutz Beeri, where 85 were killed, 26 taken hostage and four are missing, or mowing down young people fleeing a music festival, where 270 lost their lives.

"The most difficult thing is, you see images of domestic life. Parents with children in pyjamas, in their underwear. And all of a sudden, really, really violent things happening to them," an AFP journalist who viewed the film in Israel said.

One clip shows a father being killed in front of his two young sons.

A nanny cam still running in one room captures one of the boys screaming "why am I still alive?".

- 'Destroy Hamas' -

Israel's ambassador to the UN, Gilad Erdan, said in a statement on Friday that his country wanted to "to show and remind the world that we are dealing with a terrorist organisation whose goal is the destruction of Israel."

"Israel will not stop and there will be no ceasefire until we meet the goals we have set: destroying Hamas and bringing our hostages home," Erdan added after the film was shown to dozens of diplomats in New York.

Israel's efforts to circulate the film come amid growing criticism from rights groups and even unease among Israel's Western allies over the scale of its bombing campaign in Gaza since the October 7 attacks.

Hamas authorities -- who have governed the enclave since 2007 -- said Monday that more than 10,000 Gazans had been killed, mostly civilians and including 4,000 children.

Showing the film comes as Israel "is losing on the communication front", said Jerome Bourdon, a communications expert at the University of Tel Aviv.

Paris embassy spokesman Feder said there was no link between the showing of the film and the reaction to the bombardment of Gaza.

Arnaud Mercier, a communications professor in Paris, said the film was a bid by Israel to make up ground in the parallel "war of images" it is fighting against Hamas.

But he warned: "Showing the harshness of the horrors on the Israeli side won't erase the harshness of the horrors" continuing in Gaza.