The deal to hand over Tiran and Sanafir was agreed during a visit to Egypt by Saudi King Salman a year ago. It was backed by Egypt's parliament last week.

It has sparked rare protests in Egypt, with Mr Sisi being accused of "selling" territory in return for Saudi aid.

However, a legal battle over the islands' status continues.

One Egyptian court has annulled the handover decision, while another court has upheld it. The constitutional court is yet to make a final ruling on which institution had the final say.

Last week, parliament backed the deal, saying it had jurisdiction in the matter. The move sparked fresh protests in Cairo.

Mr Sisi has said the islands always belonged to Saudi Arabia and that the Saudis asked Egypt to station troops there in 1950 to protect them.

Opponents accuse Mr Sisi of violating the constitution and handing over the islands to please Saudi Arabia which has backed him financially since he led the military's overthrow of his elected Islamist predecessor, Mohamed Morsi, in 2013.

Why the Red Sea islands matter

• Sanafir and Tiran are islands that lie about 4km (2 nautical miles) apart in the Red Sea
• Tiran sits at the mouth of the Gulf of Aqaba, on a strategically important stretch of water called the Strait of Tiran, used by Israel to access the Red Sea
• The islands are uninhabited, apart from Egyptian military personnel and multinational peacekeepers
• Egyptian troops have been stationed on the islands since 1950 at the request of Saudi Arabia
• Israel captured the islands in 1956 and 1967, subsequently returning them to Egypt both times
• Abdul Fattah al-Sisi was criticised for "selling" Egyptian territory after deciding in April 2016 to hand the islands to Saudi Arabia.