Egypt's reshuffled cabinet will not be sworn in until Prime Minister Essam Sharaf recovers from a drop in blood pressure and returns to work, cabinet sources told Reuters on Tuesday.

About 15 new ministers were supposed to take the oath of office on Monday but the ceremony was delayed when Sharaf, locked in negotiations over the composition of a new cabinet demanded by protesters, was taken to a hospital.

"The new cabinet oath and negotiations over appointing other ministers is delayed until Essam Sharaf's return to the cabinet," one cabinet source said, adding that Sharaf, 59, may return by the end of this week.

The reshuffle is meant to mollify protesters camped out in central Cairo since July 8 demanding faster political and economic reforms by Egypt's ruling military council and a deeper purge of officials of former President Hosni Mubarak.

Activists pushing for a swift move to civilian rule have called the reshuffle too little, too late, saying it fails to purge the government of former Mubarak allies.

Some protesters were calling for the removal of Interior Minister Mansour el-Essawy who they say has moved too slowly to bring Mubarak and others to trial and end a culture of thuggery and impunity in the police force.

Essawy is set to keep his job in the reshuffle, which changes half of the cabinet including the foreign and finance ministers.

The reshuffle came after protests in the centre of Cairo and other cities that offered the most serious challenge yet to the army-backed interim government that took over following the overthrow of Mubarak in February.

Egypt is in a political hiatus until elections designed to usher in civilian rule later this year.

A peaceful transition will depend on how effectively the military rulers can manage pressure from the street for faster reforms and keep a lid on social tensions made worse by an economic crisis.

"What is needed is to restore the trust and the credibility of the government. The basic problem facing us now in the short run is restoring security, not just security but the perception of security," Hazem el-Beblawi, due to replace Samir Radwan as finance minister, told Reuters on Tuesday.

Security sources said late on Monday that Sharaf was admitted to a hospital in Cairo, but his condition was stable.

State news agency MENA quoted a cabinet spokesman as saying Sharaf had undergone medical tests after leaving his office on Monday evening "with fatigue after a tough day".