Egypt's new Islamist-dominated parliament has voted to select members for a body that will draft a new constitution.

However, liberal and leftist MPs withdrew, protesting that the nation's diversity would not be properly represented.

The document could decide which branch of state will effectively rule the Arab world's most populous state for years to come after decades of autocracy that ended with Hosni Mubarak's fall to a popular revolt a year ago.

The constitution will define the balance of power between parliament and president, the role of Islamic sharia law in statute and society, and the political role of the military - in power since Mubarak's removal.

The Muslim Brotherhood's Freedom and Justice Party (FJP), which controls most seats in both chambers of the parliament, said it aimed for an all-embracing constituent assembly.

In a statement the FJP said: "The party's parliamentary bloc is keen to include all political and ideological streams in the assembly, as well as represent all sectors of Egyptian society ... including youth, women and (Christian) Copt representatives."     

Those groups now occupy just a handful of seats, and liberals together hold less than one third of the mandates in parliament. Many of them say the Islamist majority is manoeuvring to eliminate alternative political streams and civil society from the 100-strong constitution-setting body.

In a statement, the liberal Egyptian Social Democratic Party said its pullout from the vote was "to protest against the FJP's continuous attempts to marginalise minorities and civil forces, a process that is clearly against the sought democracy".     

Basil Adel of the Free Egyptians, another liberal group, said his party also withdrew. He said the boycott included, in all, about 50 liberals, leftists and others from both houses.

FJP members of parliament, prior to the vote, named liberals among those they wanted included in the constituent body. The lower house has 508 seats, of which 498 are elected. The upper house has 180 elected members plus a further 90 to be appointed. Only elected members can take part in the vote for the constituent assembly. - Reuters