Four Palestinians, including a child, were killed in two Israeli strikes on Sunday despite US president Donald Trump's announcement of a breakthrough in efforts to implement last year's Gaza ceasefire agreement.

A man and his wife were killed and four people were wounded in an airstrike on an apartment in Deir al-Balah in the central Gaza Strip, while two more people, including a child, were killed in a strike on an apartment in Gaza City, medics said.

Trump said on Thursday there had been a breakthrough after Hamas agreed to disarm under a US-backed initiative to implement the ceasefire agreement reached last year in Egypt.

On Friday, Trump's Board of Peace published a 15-point roadmap outlining the final steps to implement the agreement.