Egyptian Prime Minister Essam Sharaf has begun his promised cabinet reshuffle as protests continue over the slow pace of political reform.
Foreign Minister Mohammed al-Orabi has resigned while two new deputy prime ministers have been appointed.
Among protesters' demands are for corrupt officials who served under President Hosni Mubarak to be tried.
A general who went to Tahrir Square, the heart of the revolt that toppled Mr Mubarak, was booed by demonstrators.
Under intense pressure from a new wave of protests, Mr Sharaf has embarked on what are expected to be sweeping changes to his government.
Official media say up to 15 ministers are expected to be replaced in the reshuffle. It is being seen as a purge of those with links to Mr Mubarak, who was ousted in February.
Mr Orabi, considered too close to the Mubarak regime, has resigned after less than a month in the foreign minister's post.
He was going "to spare the prime minister any embarrassment during the current negotiations on the ministerial changes", Egypt's state-run Mena news agency quoted him as saying.
Mr Sharaf, who heads a caretake administration and has limited powers under the military rulers, has appointed two new deputy prime ministers.
They are economist Hazem El Beblawi, 74, and 75-year-old Ali al-Silmi, a leader of the Wafd party, Egypt's oldest political party.
The cabinet changes have taken more than week to take effect - an indication, says BBC Cairo correspondent Jon Leyne, that Mr Sharaf is in a behind-the scenes battle with the ruling military council.
The military council have meanwhile announced that they will restrict the use of military courts to try civilians - a focus of much of the opposition's anger.
Many Egyptians are becoming impatient with the military council that replaced Mr Mubarak.
Major-General Tarek el-Mahdi went to Tahrir Square on Saturday to try to persuade some protesters to end a hunger strike.
As he spoke from a podium he was booed and had shoes shaken at him in a traditional expression of contempt, forcing him to cut short his visit.
The square was at the centre of the uprising that produced Mr Mubarak's downfall and is the focus of renewed protests.
There have also been demonstrations in other cities.
Protesters want a new government, limited power for the military council, the release of civilians being tried in military tribunals, and speedy public trials for former regime officials.