Israel's military has announced the launch of a major offensive aimed at defeating Hamas and securing the freedom of remaining hostages in Gaza.

The Israeli Defense Forces said on its Hebrew X account that it had mobilised troops for "Operation Gideon's Chariots" to seize "strategic areas" of the strip.

Hamas-run civil defence and health ministry officials say Israeli attacks have killed around 250 people since Thursday.

Israel imposed an aid blockade on the strip in March after the breakdown of a two-month ceasefire. Donald Trump, the US president, said on Friday that "a lot of people were starving" in Gaza.

The Israeli military did not use the operational name in similar posts on its English-language X account.

It said it would not stop operating "until Hamas is no longer a threat and all our hostages are home", and had "struck over 150 terror targets throughout the Gaza Strip" in 24 hours.

Israel has intensified its bombardment and built up armoured forces along the border despite growing international pressure to resume ceasefire talks and end its blockade. The launch of the operation appears to suggest all efforts have failed.

The Times of Israel said that "Gideon's Chariots" - a reference to a biblical warrior - would see the IDF take and control territory, move civilians to the south of the strip, attack Hamas and prevent it from taking control of aid supplies.

Benjamin Netanyahu, the Israeli prime minister, earlier this month said that Israel was preparing an "intense entry into Gaza" to capture and hold territory.

His government said that it would not commence until Trump had completed a tour of the Middle East. The US president left the region on Friday.

UN Human Rights Chief Volker Türk has warned that Israel's recent escalation could be considered a breach of international law.

"This latest barrage of bombs, forcing people to move amid the threat of intensified attacks, the methodical destruction of entire neighbourhoods, and the denial of humanitarian assistance underline that there appears to be a push for a permanent demographic shift in Gaza that is in defiance of international law and is tantamount to ethnic cleansing," he said.

US Secretary of State Marco Rubio said the US was "troubled" by the situation.

Victoria Rose, a British reconstructive surgeon working at Nasser hospital in Khan Younis, told BBC Radio 4's Today programme that her team were "exhausted" and had all lost a "considerable amount of weight".

"The children are really thin," she said. "We've got a lot of youngsters whose teeth have fallen out."

"A lot of them have quite significant burn injuries and with this level of malnutrition they're so much more prone to infection and they've got so much less capacity to heal."

A UN-backed assessment published on Monday found Gaza's population to be at "critical risk" of famine.

The Israeli government has repeatedly rejected claims there is a food shortage in Gaza.

Israel launched a military campaign to destroy Hamas in response to the group's cross-border attack on 7 October 2023, in which about 1,200 people were killed and 251 others were taken hostage. Hamas still holds 57.