Israel began its commemorations Monday of the one-year anniversary of Hamas's deadly October 7 attack, with an outpouring of emotion at vigils at massacre sites and rallies calling for the return of hostages.

Ceremonies and events are planned across Israel and in cities around the world to mark the anniversary of the unprecedented attack by Palestinian militants from the Gaza Strip, which claimed more than 1,200 lives.

President Isaac Herzog began the day with a moment of silence at 6:29 am -- the moment the attack began -- at Kibbutz Reim, the site of the Nova music festival where at least 370 people were killed by heavily armed Hamas fighters in the deadliest attack on October 7.

Malta's prime minister has called for restraint and dialogue.

Families of those killed attended the memorial, many of them crying, as Herzog met the crowd, an AFP correspondent reported.

On Sunday, tens of thousands of people attended events in cities around the world, both to pay tribute to the victims of Hamas's attack and to voice support for the Palestinian people after a year of war in the Gaza Strip.

"Coming to this event one year after this terrible massacre that happened on October 7, it's very touching," said organiser Solly Laniado at a ceremony Sunday in Tel Aviv to remember the victims of the Nova attack.

The anniversary comes with Israel still fighting in Gaza and engaged in a fresh war to the north in Lebanon against Hamas ally Hezbollah. It is also preparing its retaliation against Tehran over an Iranian missile attack last week, raising fears of an even wider conflict.

The Israeli army said Monday that at least four projectiles were fired from Gaza just minutes after the commemorations began, adding it had "struck Hamas launch posts and underground terrorist infrastructure throughout the Gaza Strip".

Hamas's armed wing said in a statement that its fighters had fired rockets at "enemy gatherings" at Rafah crossing, Kerem Shalom crossing and Kibbutz Holit near the border with Gaza.

The military also said sirens sounded Monday morning in northern Israel, which has seen daily rocket fire from neighbouring Lebanon. 

- Rally for hostages -

The October 7 attack by Hamas militants resulted in the deaths of 1,205 people on the Israeli side, mostly civilians, according to an AFP tally based on the latest official Israeli figures. 

Some 251 people were captured and taken as hostages to the Gaza Strip, of whom 97 are still held captive in the coastal territory, including 37 the Israeli military says are dead.

Families of hostages and supporters rallied in Tel Aviv before dawn Monday to call for their return, holding banners and placards with pictures of the captives.

During a one-week truce in late November, 105 hostages were released in exchange for 240 Palestinian prisoners.

In the western Israel city of Sderot, less than two kilometres (just over a mile) from the Gaza border, President Herzog will later on Monday lead a ceremony to remember victims of the war against Hamas.

Relatives and supporters of Israeli hostages hold images of their loved ones during a protest calling for their release in front of Prime Minister Benjamin Netanyahu residence on Monday.

Prime Minister Benjamin Netanyahu on Sunday vowed to achieve victory and said the military "completely transformed reality" in the year since Hamas's attack.

Netanyahu had pledged to "crush... and destroy" Hamas as fighting began last October, but troops have returned to several areas across Gaza where they had previously conducted operations, only to find militants regrouping.

In northern Gaza, the Israeli military said it had encircled the Jabaliya area after indications Hamas was rebuilding there despite a year of air strikes and fighting.

Rescuers said 17 people, including nine children, had been killed on Sunday by Israeli air strikes on the area.

In late September Israel turned its focus north, intensifying military action against the Iran-backed Hezbollah movement, which had been routinely sending rockets over the border from Lebanon in support of Hamas.

Israeli air strikes on targets in Lebanon have killed more than 1,110 people and forced more than one million to flee their homes.

Israel says it aims to allow tens of thousands of Israelis displaced by almost a year of Hezbollah rocket fire into northern Israel to return home.

- 'Terrible blow' -

"A year ago, we suffered a terrible blow. Over the past 12 months, we have completely transformed reality," Netanyahu said during a visit to the Lebanon border, according to his office.

Hamas on Sunday called the October 7 attack "glorious" and said the Palestinians were "writing a new history with their resistance". 

The militant group, which has ruled the Gaza Strip since 2007, launched its attack by firing thousands of rockets towards Israeli border communities in the early hours of October 7.

At the same time Hamas fighters stormed across the border and attacked nearly 50 different sites, including kibbutzim communities, army bases and the Nova music festival.

Militants killed festival-goers en masse and went door-to-door in farming communities, shooting residents dead in their homes.

Hours after the attack, Israel launched a blistering military offensive on Gaza that has reduced large swaths of the territory to rubble, and displaced nearly all of its 2.4 million residents at least once amid an unrelenting humanitarian crisis.

In Gaza, at least 41,870 people have been killed since the start of the Israeli offensive, a majority of them civilians, according to the health ministry in the Hamas-run Palestinian territory.

The figures have been deemed to be reliable by the United Nations.

- 'The world stopped' -

"If I had known that the war would last a whole year, I would never have moved from northern Gaza," Mona Abu Nahl, 51, told AFP in Deir al-Balah, in the central Gaza Strip.

"We no longer have the energy to bear all this... I would have put a tent over my destroyed house and sat down, rather than endure this humiliation, hunger and displacement," she said.

"It feels like the world stopped on October 7," said another displaced person, Israa Abu Matar, 26.

"I have grown old while watching my children hungry, scared, having nightmares and screaming day and night from the sound of the bombing and shells."

The fighting in Gaza and Lebanon has been accompanied by the threat of war with Iran, which last week fired more than 200 missiles at Israel in retaliation for the death of Hezbollah leader Hassan Nasrallah and Iranian general Abbas Nilforoushan in a September 27 strike on Beirut.

Tehran on Sunday said it had prepared a plan to hit back against any possible Israeli reprisal, before Israel's Defence Minister Yoav Gallant warned Iran it could end up looking like Gaza or Beirut.