Media playback is unsupported on your device Media caption Frank Wisner: 'This is an ideal moment for Mubarak to show the way forward'

The US state department has distanced itself from comments by a US special envoy, to the effect that Egyptian President Hosni Mubarak should stay in office during a power transition.

Spokesman Philip Crowley said Frank Wisner's views were his own, and not co-ordinated with the US government.

Hundreds of protesters are refusing to leave Cairo's Tahrir Square.

Mr Mubarak has vowed to stand down in September. Earlier, he replaced the leadership of his ruling party.

The entire politburo including his son Gamal lost their jobs.

Hossam Badrawi, a reformer and top physician, took the post of head of the policies committee, held by Gamal Mubarak, and that of secretary-general.

On Friday US President Barack Obama urged Mr Mubarak to "make the right decision" and to begin the transition "now", without explicitly saying he should step down.

Opposition demonstrators still occupy Tahrir Square, the main focus of the protests, but their numbers have fallen from Friday's huge rally there.

Late on Friday, hundreds of people attempted to prevent the army from breaking up their encampments - some lay on the ground in front of the tanks to block their progress.

The military want to re-open the square to the public and confine the protests to a small area.

But the BBC's Yolande Knell in Cairo says the city is still remarkably quiet 12 days after the protests began, as people wait to see what happens next.

Analysis Mr Wisner joined the conference via a video link from New York. He's a veteran diplomat who knows Egypt and President Mubarak well. He urged people to control their rhetoric - the more Egyptians hear demands from outside the country for Mr Mubarak to stand down, he argued, the more it could have negative consequences. The former ambassador set out the familiar US demands - changes to the Egyptian Constitution; respect for minority rights; a free press; free and fair elections and so on. Crucially he said that, in his view, Mr Mubarak should stay in office to steer these changes through. So is this the view of just a well-informed expert on Egypt? Or a glimpse from Mr Obama's special envoy of the real game plan in Washington? Does the US really want Mubarak to go?

'Critical' leadership

Mr Wisner, a former ambassador to Egypt, was sent by President Obama to Cairo on Monday, apparently to urge Mr Mubarak to announce his departure.

"We need to get a national consensus around the pre-conditions for the next step forward. The president must stay in office to steer those changes," he told the Munich Security Conference on Saturday.

"I believe that President Mubarak's continued leadership is critical - it's his chance to write his own legacy.

"He has given 60 years of his life to the service of his country, this is an ideal moment for him to show the way forward."

But in Washington, state department spokesman PJ Crowley said: "We have great respect for Frank Wisner and we were deeply appreciative of his willingness to travel to Egypt last week."

"He has not continued in any official capacity following the trip. The views he expressed today are his own. He did not co-ordinate his comments with the US government."

The resignation of leading officials of the ruling National Democratic Party was announced on state TV.

"The members of the executive committee resigned from their posts. It was decided to name Hossam Badrawi secretary general of the party," it said.

Secretary-General Safwat al-Sharif, a highly unpopular figure for the protesters, lost his post.

The TV report said President Mubarak, as party leader, had accepted the resignations.

The BBC's John Leyne in Cairo says that while the new secretary-general, Dr Badrawi, is seen as a liberal he is still close to the ruling family, and this is another indication of the turmoil in the ruling elite.

Mr Mubarak has already said he will not stand for re-election as Egypt's president in September, but insists he must stay until then to prevent chaos in the country. Protesters are demanding that he goes immediately.

US disowns Egypt envoy comments