Egypt's Vice President Omar Suleiman says President Hosni Mubarak has asked him to start dialogue with all political parties, including on constitutional and legislative reform, a key demand voiced by protesters.

Around 140 people have so far been killed in clashes with security forces in scenes that have overturned Egypt's standing as a stable country.

Protesters have called for mass rallies on Tuesday, saying one million people could take to the streets to mark a week since the uprising broke out.

Although the movement started with no clear leaders or organisation, the opposition is taking steps to organise.

The Muslim Brotherhood, an Islamist group, said it was seeking to form a broad political committee with Mohamed ElBaradei to talk to the army.

World leaders are trying to figure out how to respond to a crisis that threatens to tear up the Middle East political map.

Most have urged Mubarak to introduce reforms but stopped short of calling for him step down, preferring to emphasise their desire for stability and democratic elections.

The United States, which has poured billions of dollars of aid into Egypt since Mubarak came to power has called for an "orderly transition".

Washington has long seen Mubarak as a bulwark in the Middle East, first against communism then against militant Islam.

The crisis in Egypt follows a revolt that toppled the leader of Tunisia earlier this month and the wave of popular anger is also sweeping other countries in North Africa and the Middle East. It was the generals who persuaded Tunisia's leader to go.