Israeli forces carrying out operation in Gaza's Al Shifa hospital

The Israeli military said its forces were carrying out an operation on Wednesday against Hamas within Gaza's biggest hospital, Al Shifa.

In a statement, the military said: "Based on intelligence information and an operational necessity, IDF forces are carrying out a precise and targeted operation against Hamas in a specified area in the Shifa Hospital."

The military said: "The IDF forces include medical teams and Arabic speakers, who have undergone specified training to prepare for this complex and sensitive environment, with the intent that no harm is caused to the civilians."

Meanwhile the White House said on Tuesday its independent intelligence supported Israel's claim that Hamas was using Gaza's hospitals, including its biggest, to hide command posts and hostages while a glimmer of progress emerged in hostage negotiations.

President Joe Biden said he was in discussions daily with parties involved in talks to secure the release of hostages taken by Hamas in its cross-border rampage into Israel on Oct. 7. More than 235 people are thought to still be held by the Islamist group in Gaza.

When asked by reporters at the White House what his message to family members of hostages was, he said: "Hang in there, we're coming."

ABC News reported that progress had been made on a hostage deal. A breakthrough could come in the next 48 to 72 hours, it said, citing a senior Israeli political source.

White House spokesman John Kirby told reporters on the presidential plane, Air Force One, that intelligence confirmed the militant Hamas group, which rules Gaza, used tunnels underneath Al-Shifa and other hospitals to conceal military operations and to hold hostages.

Israel has made the same claims, which Hamas denies.

"We have information that confirms that Hamas is using that particular hospital for a command and control node" and probably to store weapons, Kirby said. "That is a war crime."

Five weeks after Israel swore to destroy Hamas in retaliation for militants' cross-border assault, the fate of Al-Shifa has become a focus of international alarm, including from Israel's closest ally, the United States.

Israeli forces have waged fierce street battles against Hamas fighters over the past 10 days, advanced into the centre of Gaza City and surrounded Al-Shifa, the seaside enclave's biggest hospital.

Kirby said that the U.S. intelligence came from a variety of methods but that he could not be specific about the evidence.

Hamas said on Telegram it rejected U.S. claims about its use of hospitals and that they "give a green light to the Israeli occupation to commit further brutal massacres targeting hospitals."

Omar Shakir, Israel and Palestine director for Human Rights Watch, said that even if Hamas was proven to be using hospitals to conduct military operations, international law required that effective warnings be given before attacks.

This meant people there needed a safe place to go and a safe way to get there, Shakir said. "It's very alarming because you have to remember hospitals in Gaza are housing tens of thousands of displaced persons."

Patients, civilians trapped inside

Hamas says 650 patients and 5,000 to 7,000 other civilians are trapped inside Al-Shifa hospital grounds, under constant fire from Israeli snipers and drones. Amid worsening shortages of fuel, water and supplies, it says 40 patients have died in recent days, including three premature babies whose incubators were knocked out.

Palestinians trapped in the hospital were digging a mass grave on Tuesday to bury patients who died and no plan was in place to evacuate babies despite Israel announcing an offer to send portable incubators, Ashraf Al-Qidra, Gaza's health ministry spokesman, said.

An Israeli officer who oversees coordination with Gaza told Reuters earlier that he had been in contact with Al-Shifa's hospital director and presented a plan to evacuate the babies through a safe corridor, possibly to Egypt. He said he was awaiting a response.

Reached by telephone inside the hospital compound, Qidra said that so far no arrangements had been established to carry out any evacuation. "The occupation is still besieging the hospital and they are firing into the yards from time to time," he said.

Qidra said there were about 100 bodies decomposing inside and no way to get them out.

"We are planning to bury them today in a mass grave inside the Al-Shifa medical complex. It is going to be very dangerous as we don't have any cover or protection from the ICRC," he told Reuters, referring to the International Committee of the Red Cross/Crescent.

Earlier Israel denied that the hospital is under siege and said its forces allow exit routes for those inside. 

U.N. Secretary-General Antonio Guterres was deeply disturbed by the "dramatic loss of life" in the hospitals, his spokesman said. "In the name of humanity, the secretary-general calls for an immediate humanitarian ceasefire," the spokesman told reporters.

Medical officials in Hamas-run Gaza say more than 11,000 people are confirmed dead from Israeli strikes, around 40% of them children, and countless others trapped under rubble. Around two-thirds of Gaza's 2.3 million people have been made homeless, unable to escape the territory where food, fuel, fresh water and medical supplies are running out.

Israel says Hamas killed 1,200 people in the Oct. 7 rampage. The United States and Britain imposed a fresh round of sanctions on Hamas on Tuesday.

Brett McGurk heading to the region

Shortly after Biden's remarks about the hostages, the White House said Biden's top Middle East adviser, Brett McGurk, was heading to the region for talks with officials in Israel, the West Bank, Qatar, Saudi Arabia and other nations. Efforts to win the hostages' release will be among the topics on his agenda.

Hamas leader Ezzat El Rashq said on Telegram Israel was not serious about winning the hostages' freedom "but is stalling in order to gain more time to continue its aggression."

The armed wing of Hamas said it was ready to free up to 70 women and children held in Gaza in exchange for a five-day ceasefire. Al-Qassam Brigade spokesman Abu Ubaida said Israel had asked for 100 to be freed.

There was no immediate public response from Israeli Prime Minister Benjamin Netanyahu's office.

Relatives of hostages set off from Tel Aviv on a days-long protest march to Jerusalem to plead for more government action.

Yuval Haran, from Kibbutz Be'eri where Hamas fighters killed scores of civilians including his father, said he was marching out of desperation to free seven family members.

"For 39 days we have been in infinite anxiety. We are living this pain each and every moment. And I cannot keep sitting down and waiting," he said. "They must be brought home now."

In Washington, tens of thousands of demonstrators gathered on Tuesday for a "March for Israel" to show solidarity with Israel in its war with Hamas and condemn rising antisemitism.