The US has told Israel it must be fully "transparent" over an air strike that reportedly killed at least 35 people at a central Gaza school packed with displaced people on Thursday morning.

Local journalists told the BBC that a warplane fired two missiles at classrooms on the top floor of the school in the urban Nuseirat refugee camp.

The Israeli military said it conducted a "precise" strike on a "Hamas compound" in the school, but Gaza’s Hamas-run Government Media Office denied the claim.

US State Department spokesperson Matthew Miller said Israel must publicly identify the Hamas fighters it claims to have killed. Israel frequently identifies militants it targeted in airstrikes, but it is rare for the US to urge it to do so.

"The government of Israel has said that they are going to release more information about this strike, including the names of those who died in it," Mr Miller said.

"We expect them to be fully transparent in making that information public."

On Thursday evening, Israeli army spokesperson Daniel Hagari gave the names of nine Hamas and Islamic Jihad fighters he said were killed in the strike. He claimed more would be identified after work to “verify the information”.

The strike comes just a week after 45 people were killed in an Israeli strike in the Gazan city of Rafah.

Local journalists and residents said Thursday's strike took place in the early hours of Thursday at al-Sardi school, which is in a south-eastern area of the densely-populated, decades-old camp, where the UN agency for Palestinian refugees, Unrwa, provides services.

Videos shared on social media showed the destruction of several classrooms in one of the school's buildings, as well as bodies wrapped in white shrouds and blankets.

Dead and wounded people were rushed to the al-Aqsa Martyrs’ Hospital, in the nearby town of Deir al-Balah, which has been overwhelmed since the Israeli military began a new ground operation against Hamas in central Gaza this week.

The BBC is working to verify the details of the strike in Nuseirat camp. Reports on the exact number of dead have varied.

Gaza’s Hamas-run health ministry said 40 people were killed, including 14 children and nine women, and 74 others were injured.

Meanwhile, Unrwa's commissioner general, Philippe Lazzarini, said that at least 35 people were killed and many more injured. The agency’s director of communications, Juliette Touma, told the BBC that "the figures are coming from our own Unrwa colleagues on the ground".

Witnesses described a scene of devastation following the strike.

“I was asleep when the incident occurred. Suddenly, we heard a loud explosion and shattered glass and debris from the building fell on us,” Udai Abu Elias, a man who was living at the school, told BBC Arabic.

“Smoke filled the air and I couldn't see anything. I didn't expect to make it out alive. I heard someone calling for survivors to come out from under the rubble. I struggled to see as I stumbled over the bodies of the martyrs.”

Unrwa said 6,000 displaced people were sheltering in the school complex at the time. Many schools and other UN facilities have been used as shelters by the 1.7 million people who have fled their homes during the war, which has lasted almost eight months.

UN Secretary General Antonio Guterres condemned the strike through a spokesperson, saying that UN premises must be "inviolable" and protected by "all parties" during conflicts.

In a statement, the Israel Defense Forces (IDF) said jets had conducted a "precise strike on a Hamas compound embedded inside" the school. An annotated aerial photograph highlighted classrooms on two upper floors of the building, which the IDF said were the “locations of the terrorists”.

But speaking in Washington late on Thursday, Mr Miller said: "We've seen the claims that 14 children were killed in this strike, and certainly, when you see - if that is accurate - that 14 children were killed, those aren't terrorists."

Meanwhile, US officials have continued to lobby for a what US President Joe Biden called an Israeli ceasefire proposal.

The three-part plan would begin with a six-week ceasefire in which the Israeli military would withdraw from populated areas of Gaza. There would also be a "surge" of humanitarian aid, as well as an exchange of some hostages for Palestinian prisoners.

The deal would eventually lead to a permanent "cessation of hostilities" and a major reconstruction plan for Gaza. Germany, France and Britain re-affirmed their support for the deal in a joint statement with the US on Thursday and called for "an enduring end to the crisis".

CIA Director William Burns met mediators from Egypt and Qatar in Doha on Thursday to discuss the plans, but senior Cairo officials told the Reuters news agency that there had been no sign of a breakthrough on the deal.

At least 36,470 people have been killed in Gaza in almost eight months of fighting, according to the Hamas-run health ministry.

Hamas killed about 1,200 people and took 251 others hostage during its 7 October attacks on southern Israel.