Egypt's military rulers have issued a decree giving presidential powers to Prime Minister Kamal al-Ganzouri.
But the country's official news agency says the army is keeping control of military affairs and the judiciary.
Mr Ganzouri, 76, who served as prime minister under Mr Mubarak, was appointed by the ruling military council when the previous cabinet resigned last month during clashes with protesters who were demanding an end to military rule.
A new cabinet was named on Wednesday.
The military has been in charge in Egypt since President Hosni Mubarak was overthrown by a popular uprising in February.