David Cameron called tonight for a move to "a move to civilian and democratic rule" in Egypt following the dramatic resignation of President Hosni Mubarak.
The Prime Minister said the departure of the 82-year-old Egyptian strongman after 30 years in power offered his country a "really precious moment of opportunity".
Speaking on the steps of No 10, he said the new government should start to put in place "the building blocks of a truly open, free and democratic society".
Mr Cameron hailed the achievement of the demonstrators whose 18 days of mass protests finally forced Mr Mubarak to quit the office of president which he had appeared so determined to hang on to.
"Today has been a remarkable day, particularly for those people in Tahrir Square and elsewhere, who have spoken out so bravely and so peacefully for change in their country," the Prime Minister said.
"Egypt now has a really precious moment of opportunity to have a government that can bring the country together. And as a friend of Egypt and the Egyptian people we stand ready to help in any way that we can.
"We believe that it must be a government that starts to put in place the building blocks of a truly open, free and democratic society. And of course what has happened today should only be the first step.
"Those who now run Egypt have a duty to reflect the wishes of the Egyptian people and, in particular, there really must be a move to civilian and democratic rule as part of this important transition to an open, democratic and free Egypt."
His comments reflect concern in Western capitals that the handover of power by Mr Mubarak to the armed forces should not mark the start of a prolonged period of military rule.Reuse content