About 500 Palestinians have been killed in a blast at a Gaza hospital that Palestinian health authorities say was caused by an Israeli air strike but the Israeli military blamed on a failed rocket launch by a Palestinian militant group.

Health authorities in the Hamas-ruled Gaza Strip said that an Israeli air strike caused the blast while Israel’s military attributed it to a failed rocket launch by the Palestinian Islamic Jihad militant group.

Tuesday’s blast was the bloodiest single incident in Gaza since Israel launched an unrelenting bombing campaign against the densely populated territory in retaliation for a deadly cross-border Hamas assault on southern Israeli communities on October 7.

It took place on the eve of a visit by US President Joe Biden to Israel to show support for the country in its war with Hamas, which rules the Gaza Strip.

Before the blast, health authorities in Gaza said at least 3000 people had died in Israel’s 11-day bombardment that began after Hamas’ October 7 rampage in which an estimated 200 people were taken back into the Gaza Strip as hostages.

Hamas said the bombing mostly killed people left homeless by Israel bombardments, and that the dead included patients, women and children.

“There are scores of dismembered and crushed bodies, baths of blood,” said Izzat El-Reshiq, a senior Hamas member.

Video obtained by Reuters showed several full ambulances arriving at another Gaza hospital carrying people injured at Al-Ahli al-Arabi hospital. One man was staggering, bleeding heavily from the head. A boy was being carried on a stretcher.

There were competing claims and denials from Israeli and Palestinian officials over who was responsible.

The Palestinian Authority health minister, Mai Alkaila, accused Israel of a massacre. A Gaza civil defence chief said 300 people were killed and a health ministry official said 500 were killed.

Israeli Prime Minister Benjamin Netanyahu minced no words in blaming Palestinian militants for the explosion.

“The entire world should know: It was barbaric terrorists in Gaza that attacked the hospital in Gaza, and not the IDF,” he said, referring to the Israel Defence Forces. “Those who brutally murdered our children also murder their own children.”

The IDF blamed a Palestinian militant group called Palestine Islamic Jihad which, like Hamas, is viewed by the US as a foreign terrorist organisation.

“Following an additional review and cross-examination of the operational and intelligence systems, it is clear that the IDF did not strike the hospital in Gaza,” IDF spokesperson Rear Admiral Daniel Hagari said in a video statement.

“The hospital was hit as a result of a failed rocket launched by the Islamic Jihad terrorist organisation.”

In Washington, the Pentagon said it was aware of the reports about the hospital being hit but had no details.

Israel has imposed a total blockade on Gaza, halting food, fuel and medical supplies, which are rapidly running out.

Scores of trucks carrying vital supplies for Gaza headed towards the Rafah crossing in Egypt on Tuesday, the only access point to the coastal enclave outside Israel’s control, but there was no clear indication that they would be able to enter.

Earlier on Tuesday, German Chancellor Olaf Scholz arrived in Israel to show solidarity with the country following attacks from Hamas.

Scholz said on Tuesday that “Germany stands firmly by Israel’s side,” in a post on X.

The German chancellor is the second head of government to visit the country since the Hamas attack 10 days ago, after Romanian Prime Minister Marcel Ciolacu arrived in Israel earlier on Tuesday.

US Secretary of State Antony Blinken announced Biden’s planned visit at the end of hours of talks with Netanyahu, in which he said Netanyahu had agreed to develop a plan to get humanitarian aid to Gaza civilians.

He gave no details.

Biden will “hear from Israel what it needs to defend its people” when he visits on Wednesday, Blinken said.

He will also hear how Israel will carry out operations in a way that minimises civilian casualties and lets humanitarian aid into Gaza to help civilians “in a way that does not benefit Hamas”.

The United Nations agency for Palestinian refugees, UNRWA, said only about 14 per cent of Gazans had access to water through a single pipe to Khan Younis that Israel allowed to open for three hours on Monday.

– AAP