On Sunday, the Muslim Brotherhood said 11 members were arrested as parliament was asked to approve changes in the constitution. At least 50 Brotherhood members, including several leaders, have been detained as the movement called for boycott of the parliamentary vote on the constitutional amendments.

Egyptian parliamentarian Hazem Farouk, a Brotherhood member, said the Mubarak crackdown was meant to prevent the movement from distributing health and welfare services in Cairo. Farouk said Egyptian police raided a Brotherhood office on March 16 that was distributing medical supplies in a Cairo neighborhood.

"This is all part of the same pressure," Farouk said.

Opposition sources said many Brotherhood members remained in detention despite an order from an Egyptian prosecutor for their release. They said security agencies controlled by the Interior Ministry have ignored directives from Egypt's judicial system.

The revisions to the constitution discussed by parliament on Sunday were meant to block the Brotherhood from gaining power, opposition sources said. They said one amendment would ban political activities based on religion. The revisions were scheduled to be presented for a referendum in April.

"The Muslim Brotherhood is organized, but has no influence as an organization," Mustafa Faqi, chairman of parliament's Foreign Relations Committee and a Brotherhood critic, said. "It has no program. It just promotes general feelings."

The London-based Amnesty International termed the 34 constitutional amendments the "greatest erosion of rights in 26 years." Under the revisions, Amnesty said, authorities would have unprecedented powers of detention, restrict public gatherings, prevent judicial monitoring of elections and prosecute dissidents in military courts.

"They will enrich the long-standing system of abuse under Egypt's state of emergency powers and give the misuse of those powers a bogus legitimacy," Hassiba Hadj Sahraoui, deputy director of Amnesty's Middle East and North Africa program, said.

For his part, Mubarak said the revisions have been misrepresented by opposition groups and Western human rights activists. He said the so-called anti-terror amendment would not erode Egypt's democracy.

"It is sad to see that the debate about it has not been objective," Mubarak said in an interview to the state-owned Akhbar Al Youm on March 17. "I want to tell people that these amendments came as a response to a public desire for more political reform."