At least 20 Palestinians were killed on Friday in an Israeli airstrike in Gaza, according to local health officials, as U.S. President Donald Trump said he expected Hamas to respond to his "final proposal" for a ceasefire in Gaza in the next 24 hours.

Dr Marwan Sultan was killed along with several family members in a strike on his home, the health ministry says.

President Trump raised expectations last week when he told reporters in the Oval Office that there could be a ceasefire agreement within the next week.