Media playback is unsupported on your device Media caption President Obama: "An orderly transition must be meaningful, it must be peaceful and it must begin now"

US President Barack Obama has said an orderly political transition "must begin now" in Egypt and lead to free and fair elections.

His statement followed the announcement by Egypt's President Hosni Mubarak that he would not stand for re-election.

Earlier, the US had told Mr Mubarak not to stand for re-election nor to put forward his son, the BBC learned.

The Obama adminstration's message was carried to Cairo on Monday by former US Ambassador to Egypt Frank Wisner.

The White House had previously said it was not Mr Obama's place to pick Egypt's leader.

On Tuesday night, Mr Mubarak - who has ruled Egypt for the past three decades - said he would not stand for re-election.

However, he said nothing about his son, Gamal Mubarak, whom he is seen as having positioned to be his successor.

Analysis The US was trying to make it clear to Mr Mubarak that he should go, without necessarily spelling it out. The question is, what should Washington do now? It realises what Mr Mubarak has offered is not enough for the crowds of Egyptians calling for him to go. There seems to be a consensus among Washington and its allies that he should go - is the US going to go back to him with that message? What the US says in public is that it is up to the Egyptian people to decide who they want as their leader. It is very keen not to be seen as interfering, as that has often been a criticism of American foreign policy. What the US is worried about in the short term is a vacuum and chaos, as tension could rise very quickly on the streets. In the long term, Washington would want to see a government in place that is friendly to the US.

Mr Obama's televised statement followed discussions with his national security advisers in Washington on Tuesday.

While he did not say Mr Mubarak should stand down immediately, he said "an orderly transition must be meaningful, it must be peaceful and it must begin now".

Mr Obama said he had spoken to the Egyptian leader after his announcement in Cairo and that Mr Mubarak recognised "that the status quo is not sustainable and a change must take place".

The US president praised Egypt's military "for the professionalism and patriotism that it has shown thus far in allowing peaceful protests while protecting the Egyptian people" and urged it to continue that approach.

He stressed that it was up to the Egyptian people to choose their leaders, and that the US would continue to offer support and friendship to them.

BBC state department correspondent Kim Ghattas, in Washington, says the US hopes Mr Mubarak has figured out on his own that he has got to go now, rather than stand down after the presidential election in September.

Washington has sought to make it clear that it understands the grievances of the Egyptian people, while also making clear it wants them to be able to pick their next leader, our correspondent says.

'Step aside'

Earlier on Tuesday, US Senator John Kerry, a top Washington foreign policy voice, urged Mr Mubarak to pledge that neither he nor his son would stand in the presidential election.

It remains to be seen whether this is enough to satisfy the demands of the Egyptian people for change US Senator John Kerry, Senate Foreign Relations Committee

Writing in the New York Times, Mr Kerry said Mr Mubarak had to accept Egypt's stability "hinges on his willingness to step aside gracefully".

Responding after Mr Mubarak's statement on Tuesday evening, he said: "I believe that President Mubarak should now work with the military and civil society to establish an interim caretaker government.

"It remains to be seen whether this is enough to satisfy the demands of the Egyptian people for change."

Mr Kerry said the Egyptian people had made clear that they wanted a future offering greater democracy and greater economic opportunity.

"Now, that future belongs to them to shape. The Egyptian people are writing the next chapter of Egyptian history," he said.

The US state department on Tuesday ordered the departure of all non-emergency US government personnel and their families from Egypt and said it would continue to help any US citizens wishing to leave.

About 1,600 US citizens and their family members have been evacuated since Monday, the state department said.