By Steve Holland and Nidal al-Mughrabi
TEL AVIV/GAZA (Reuters) -U.S. President Joe Biden pledged to help Israel and the Palestinians during a lightning visit on Wednesday, but a deadly hospital blast that he ascribed to an errant rocket fired by Gaza militants derailed talks to prevent the war spreading.
Raising fears of wider instability, protesters staged anti-Israeli demonstrations around the Middle East over the fireball that engulfed the Gaza Strip's Al-Ahli al-Arabi hospital late on Tuesday, which Palestinian officials said killed 471 people.
They blamed what they said was an Israeli air strike, while Israel said it was caused by a failed rocket launch by the Islamic Jihad militant group, which denied responsibility.
Biden promised more aid to Israel at the end of his impromptu one-day visit to the country, which is bombarding Gaza to try to root out militants from its ruling Hamas group after they killed 1,400 Israelis in a cross-border assault on Oct. 7.
He said of the hospital blast: "Based on the information we have seen today, it appears the result of an errant rocket fired by a terrorist group in Gaza."
In Washington, the White House National Security Council echoed Biden, saying the U.S. assessment was based on analysis of overhead imagery, intercepts and open source information.
Arab leaders responded to the loss of life at the hospital, which they blamed on Israel, by cancelling a summit with Biden in Jordan.
DON'T BE CONSUMED BY RAGE, BIDEN SAYS
Biden said the United States would do everything it could to ensure Israel was safe while also urging Israelis not to be consumed by rage, reiterating that the vast majority of Palestinians were not affiliated with Hamas.
The Gaza health ministry said 3,478 Palestinians have been killed and 12,065 injured in Israeli air strikes on the besieged enclave since Oct 7.
Biden said the U.S. would provide $100 million in new funding for humanitarian aid to Palestinians in Gaza and the Israeli-occupied West Bank.
"What sets us apart from the terrorists is we believe in the fundamental dignity of every human life," Biden said. If that was not respected, "then the terrorists win."
In a less than eight-hour visit, he also said he would ask Congress for an "unprecedented" aid package for Israel this week, although no action is possible until the House of Representatives elects a new speaker.
Biden faced intense pressure to secure a clear Israeli commitment to let aid into Gaza from Egypt, to ease the plight of civilians in the small, densely populated coastal enclave.
At the end of Biden's visit, Israeli Prime Minister Benjamin Netanyahu's office put out a statement saying Israel would let food, water and medicines reach southern Gaza via Egypt. Israel reiterated it would not let aid in from Israel until Hamas released about 200 hostages seized during the Oct. 7 attack.
BIDEN SUMMIT WITH ARABS CANCELLED
Biden's Middle East trip was designed to calm the region, but Jordan called off his planned summit there with Egypt and the Palestinian Authority after the hospital blast. Instead he was expected to hold phone calls with Jordan and Egypt from Air Force One on his way home.
The accounts of destruction at the hospital were horrific even by the standards of the past 12 days, which have confronted the world with relentless images, first of Israelis murdered by Hamas gunmen in their homes and then of Palestinian families buried under rubble from Israel's retaliatory strikes.
Rescue workers scoured blood-stained debris for survivors. The Gaza health ministry put the death toll at 471, though Israel disputed the figure. Palestinian ministry spokesperson Ashraf Al-Qudra said rescuers were still recovering bodies.
"We don't know what it was, but we found out what it could do, after it targeted children, who were cut into pieces," said Mohammad Al-Naqa, a doctor at the hospital who said 3,000 people were sheltering there when it was hit.
Israel last week ordered more than one million civilians in northern Gaza to evacuate to avoid being hit in attacks on Hamas strongholds there, and displaced Palestinians face a worsening humanitarian crisis.
The immediate Israeli strategy, said three regional officials, is to destroy Gaza's infrastructure, even at the cost of high civilian casualties, push the enclave's people towards the Egyptian border and go after Hamas by blowing up its labyrinth of underground tunnels.
Neighboring Egypt and Jordan have squarely rejected the notion that Palestinian refugees could move into their territories. Egyptian President Abdel Fattah al-Sisi and Palestinian leaders in the occupied West Bank on Wednesday denounced forced displacement of Gaza civilians. Palestinian leaders called it a "red line" that could not be crossed.
FURY ACROSS MIDDLE EAST
World leaders from U.N. Secretary General Antonio Guterres to Russian President Vladimir Putin denounced the Gaza hospital blast in statements that nonetheless avoided addressing who was to blame.
The blast unleashed anger across the Middle East.
In Lebanon, security forces fired tear gas and water cannon at protesters throwing projectiles near the U.S. embassy north of Beirut. State-sponsored marches were held across Iran, backer of Hamas and Israel's sworn foe, with demonstrators carrying banners that read "Death to America" and "Death to Israel".
Palestinian officials said Israeli forces shot dead two Palestinian teenagers near Ramallah in the West Bank during widespread protests.
There were new clashes on Israel's border with Lebanon, part of the deadliest violence between the Iran-backed Hezbollah movement and Israel since the last all-out war in 2006. Hezbollah said two of its fighters were killed.