An Israeli air strike on a school sheltering displaced families in Gaza killed 10 people on Wednesday.

Israeli strikes killed 36 people across the besieged territory, while Germany, France and Britain urged Israel to end its blockade on aid entering.

Since a January ceasefire collapsed on March 18, Israeli attacks have killed more than 1,600 Palestinians, many of them civilians, according to the Gaza health authorities, and hundreds of thousands have been displaced as Israel seized what it calls a buffer zone of Gaza's land.

Israel has also imposed a blockade on all goods into Gaza, including fuel and electricity, since the beginning of March.

Medics said the air strike on the Yaffa School in the Tuffah area of Gaza City set fire to tents and classrooms.

The Israeli military said Hamas and allied group Islamic Jihad were operating within the school and that it took precautions to reduce harm to civilians before it struck there.

Some furniture was still in flames several hours after the strike as people sifted through blackened classrooms and the schoolyard in search of their belongings.

The foreign ministers of Germany, France, and Britain jointly called on Israel to adhere to international law and allow the unhindered passage of humanitarian aid into Gaza.

They also urged for the ceasefire to be restored and for remaining hostages held by resistance group Hamas to be released.

"Humanitarian aid must never be used as a political tool and Palestinian territory must not be reduced nor subjected to any demographic change," the ministers said in a statement.

The Gaza Health Ministry said an Israeli missile hit the upper building of the Durra Children's Hospital in Gaza City, damaging the intensive care unit and destroying the solar panel system that feeds the facility with power. No one was killed.

Hamas says it is prepared to free the hostages only as part of a deal that ends the war, but it has rejected demands to lay down its arms.