The British Embassy in Cairo has suspended its public services for security reasons today.
The office of the British Consulate-General in Alexandria will continue operating as normal.
An Egyptian court has issued preliminary death sentences for 185 people over an attack on a police station last year.
Former Egyptian president Hosni Mubarak was today cleared of ordering the killing of protesters during the uprising that ended with his removal from power.
Having served two years of a life sentence, Mr Mubarak was given a retrial where he was today acquitted.
His supporters were delighted but the verdict provoked fury in some quarters.
ITV News Correspondent Gareth Owen reports.
An Egyptian court has cleared ousted President Hosni Mubarak of charges related to corruption, and dropped the case against him for his involvement in killing protesters during the 2011 revolt that removed him from power.
Mubarak's interior minister Habib el-Adly and six aides were also cleared of charges related to the killing of protesters in 2011.
An Egyptian navy ship has suffered a "terrorist" attack, leaving five servicemen injured and eight others missing, the AFP news agency reported.
Military officials said dozens of "armed assailants" attacked the vessel on Wednesday off the coast of the north-east province Damietta.
The air force helped destroy four of the boats used by the suspected militants, the military said.
Thirty-two people were arrested and are being questioned, officials said.
Egyptian terror group Ansar Bayt al-Maqdis has sworn allegiance to the Islamic State, they said in a statement tonight.
Ansar's insurgency in the Sinai Peninsula has killed hundreds of people. They have previously said they looked to ISIS for inspiration.
At least 25 members of the Egyptian security forces were killed in a car bomb attack at a checkpoint in the Sinai Peninsula, security sources said.
David Cameron has urged Egyptian president El Sisi to "ensure human rights are respected" in the country and stressed the importance of their role in tackling Islamist extremism.
The Prime Minister met President El Sisi today in New York.
The Prime Minister stressed Egypt's pivotal role in the region, both economically and in the fight against Islamist extremism. He stressed the UK's wish to see a stable, prosperous and democratic Egypt as Egypt's biggest foreign investor.
"He urged Egypt to ensure human rights are respected in Egypt in the fight against extremism, including addressing the large numbers of people in custody and the widespread use of death sentences," the spokesperson added.
Former Egyptian president Mohammed Morsi has been charged with endangering national security by leaking state secrets and sensitive documents to Qatar.
Qatar had supported Morsi and the Muslim Brotherhood and security sources said last month that Egypt was investigating him in connection with documents they said were leaked to Qatar and its Al Jazeera news channel.
At least 19 people have died in Egypt after two minibuses fell into a canal near the tourist city of Luxor early this morning, state-run newspaper Al Ahram reported.