"We believe there is a high threat from terrorism and terrorists continue to plan attacks," the warning read. "Attacks could be indiscriminate and occur without prior warning."
Egyptian news website Ahram Online reports militant group Ansar Beit al-Maqdis claimed responsibility for a Sunday attack in Sinai during the weekend, which left three South Korean tourists and an Egyptian driver dead.
The FCO said in its travel warning it was advising against all but essential travel to the region, except for the resort city of Sharm el-Sheik.
The warning said most attacks in the region have been aimed at security forces, though attacks on foreigners "cannot be ruled out."
Last week, Egypt's official MENA news agency said a gas pipeline was attacked in the region, the fourth such attack this year. No injuries were reported and there were no claims of responsibility for that attack.