David Cameron has said the Government is urgently looking into reports that a British national has been killed in Gaza.
The Prime Minister said the apparent death of the man in an Israeli air strike underlined the need for "an immediate unconditional humanitarian ceasefire observed properly by both sides".
Cameron said during a visit to the Loos Cemetery in northern France, "I'm extremely concerned about these reports and we are doing everything we can to get to the bottom [of them] and find out exactly what has happened."
"This slaughter, this killing has got to end," he added.
There have been two days of quiet in Gaza. No rockets or missiles, no more destroyed houses, no more ambulance sirens screaming.
A three-year-old girl has been rescued from Gaza and brought to London for life-saving heart surgery.
A small team of NHS doctors and surgeons is travel to Gaza to set up facilities and establish how best to use specialists and equipment.