|Almost 100 MPs boycotted the vote on the constitutional amendments on Monday [AP]|
Egypt's opposition Muslim Brotherhood has decided it will not take part in a referendum on changes to the constitution due to be held on March 26.
"We will boycott the referendum and we call on the citizens to boycott it as well," Essam el-Erian, a spokesman for the movement, said.
The Muslim Brotherhood, which is officially banned as a political party, is likely to be hardest hit by the changes, which will prohibit political activity based on religion.
The changes would also allow the president to dissolve parliament unilaterally and would reduce the role of judges in overseeing elections, which have been marred by complaints of widespread irregularities.
"All referendums are rigged, and in these amendments the opinions of the political and nationalist forces or opposition parties were not respected. They are just being dictated by one party," el-Erian said.
The 34 constitutional amendments were passed by parliament on Monday but must be approved in a popular vote.
"It is really sad to see Egypt, a republic country, turned into a kingdom"
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The ruling party of Hosni Mubarak, the president, says the reforms will strengthen democracy and help fight terrorism. The anti-terrorism clause appears to give police sweeping powers of arrest and surveillance.
Nearly 100 mainly politicians, mainly from Islamic parties, boycotted Monday's vote, choosing instead to protest outside parliament with black banners opposing the changes.
Although officially illegal, the Muslim Brotherhood has 88 MPs in the 454-seat parliament after they ran as as independents in 2005.
Security forces arrested dozens of Brotherhood members in the days leading up to the ballot, stepping up a three-month crackdown during which about 270 brotherhood members were detained.
Khairat el-Shatir, the movement's third-in-command, was among those arrested. He has been charged, along with 39 others, with money-laundering and terrorism.
Amnesty International, the London-based human rights organisation, has called the amendments "the greatest erosion of human rights" since emergency laws were put in place in 1981 after the killing of the president, Anwar Sadat.
The United States also offered mild criticism of its ally, saying it had "concerns" that some of the amendments fell short of the Egyptian government's stated aims of lifting the state of emergency, reining in police powers and allowing political freedoms.
"If you look at some of the amendments that have been finally passed by the lower house, it does certainly raise questions about whether or not the Egyptian government has in fact met its own standards," Sean McCormack, US state department spokesman, said.