Britain will send a charter flight to Cairo to bring home British nationals, the foreign secretary announced today, but passengers will have to pay to use the service.

Speaking in parliament, William Hague said he had arranged for an aircraft to be sent to supplement commercial travel. The Foreign Office later said it would cost around £300 for a seat on the flight.

Days of protests in Egypt have culminated in up to a million people taking to the streets today, the largest demonstration so far against President Hosni Mubarak's regime.

"We have been advising people in Cairo or Alexandria or Suez to leave if they can, if they don't have any pressing reason to remain," Hague told parliament.

The foreign secretary said the "vast majority" of those seeking to leave have been able to do so on commercial flights, but he added: "I have decided to send a charter flight to Cairo tomorrow, to allow those who wish to leave to do so. I will send further flights if we see a need to do so."

Although the flight will leave the UK tomorrow, it will not return from Cairo until Thursday, a spokeswoman for the Foreign Office said. Departure and arrival times had not been finalised yet.

The foreign office took to Twitter and its website to warn that there would be a £300 charge for using the charter flight. Passengers will be able to pay at the airport, it said.

The Foreign Office has advised against all but essential travel to Cairo, Alexandria, Luxor and Suez.

Those wishing to travel on the Foreign Office's charter flight should register by calling 020 7008 8765.