Muhammad Mahdi Akif said on Tuesday he expects parliament, dominated by the ruling party, to nominate 76-year-old Mubarak in May for a fifth six-year presidential term, which the Brotherhood and other opposition groups oppose.
Mubarak, who has ruled Egypt since 1981, has strongly hinted but not confirmed that he will seek the fifth term. The candidate parliament picked for the post is put to a public referendum in September.
Egyptians expect Mubarak to stand again, mainly because he has no obvious successor.
Akif said: "President Husni Mubarak grasps all the matters of state in his own hand - executive, judicial or legislative. We are in a police state governed by one man."
The Jamal factor
Jamal Mubarak has become a prominent figure in the ruling party, but observers say he has yet to build up enough support to vie for the presidency.
When they want to bring Jamal,
they will bring him, Akef says
Mubarak has dismissed the idea he would hand power to his son. But Jamal could pursue the presidency through constitutional means.
"When they want to bring [Jamal], they will bring him," Akif said. "All the while there is emergency law, all the while there is the political parties law, all the while there are political prisoners ... they can do anything.
"Don't forget that we are a state which is almost a police state. Everything is in the hands of security," he added.
Egypt's emergency laws allow the state to detain suspects without charge and political parties must be licensed by a committee dominated by the ruling party.
The Brotherhood, which is officially banned, and other Egyptian opposition groups are calling for changes to Egypt's constitution to allow than one candidate to run for president.
Elections for parliament, which currently picks the candidate, will be held after the presidential referendum.
Many Egyptian groups oppose a
fifth term for President Mubarak
"I am one of those who encourages elections. But are these elections, that go on in the shadow of emergency laws, or the political parties law or military courts, are these considered elections? No, they are not," Akif said.
"But I enter elections, despite these conditions, so that I can make my voice heard."
Muslim Brotherhood members standing as independents won 17 seats in the 2000 parliamentary elections, despite reported police harassment of their supporters.
Akif said the Muslim Brotherhood had yet to decide how many candidates to field in the elections. It ran fewer than 100 in the 2000 polls.