The Government is working to establish the status of UK citizens in Israel after a British man serving in the country’s army was killed during attacks by Hamas.
Rishi Sunak condemned an “appalling act of terror” by Palestinian militants as the death toll climbed to 700 in Israel and 300 in Gaza.
Among those killed was 20-year-old Nathanel Young, a Briton serving in the Israeli Defence Services who died on the Gaza border on Saturday.
Two other UK nationals – 26-year-old Jake Marlowe, who went to the same London school as Mr Young, and photographer Dan Darlington – are also believed to be missing.
Speaking to reporters at his Chequers country residence, the Prime Minister said he had spoken with the Israeli premier earlier on Sunday to offer the UK’s ongoing support, adding: “Terrorism will not prevail.”
Asked what assistance is being provided to British citizens caught up in the conflict, he told reporters: “I know that there will be families who are anxious about their loved ones.
“I want to reassure them that the Foreign Office and the Government here is in close contact with our Israeli counterpart to establish the status of any British nationals on the ground.”
It is understood the Government is assisting the families of several individuals in Israel and the Occupied Palestinian Territories.
The Foreign Office has advised against all but essential travel to the region due to the conflict.
Mr Young, who was a former pupil at JFS Jewish School in north London, was killed following a surprise attack by Palestinian militants which caught Israel off-guard on a major holiday.
His family said they were “heartbroken” while the father of Mr Darlington said he believes his son, who was visiting from his home in Berlin, Germany, is missing.
Mr Marlowe was reported missing while providing security at a music festival near Kibbutz Re’im, close to the Gaza border.
Labour leader Sir Keir Starmer said his thoughts were with Mr Young’s family at this “grave and significant moment”, and labelled the incursion a “terrorist attack”.
The Israeli Government declared war on Sunday, with the military saying it had hit at least 800 targets in Gaza so far. The country’s rescue service Zaka said its paramedics removed about 260 bodies from a music festival attended by thousands that came under Hamas attack.
Previous conflicts in the Middle East have seen an increase in antisemitism in the UK, the Board of Deputies of British Jews warned, as it confirmed it was in touch with Government to ensure the Jewish community is supported.
All UK Government buildings were asked to light up in Israeli blue and white on Sunday evening, with the country’s flag projected on to the outside of No 10 in a show of support.
A Foreign Office spokeswoman said they would not comment on individual cases, but added: “However, we can confirm we are in contact with, and assisting, the families of several individuals in Israel and the OPTs (Occupied Palestinian Territories).
“The safety of all British nationals continues to be our utmost priority and we urge everyone to continue to follow our travel advice which is updated regularly.”