Opposition lawmakers boycotted an opening parliamentary debate Sunday on constitutional amendments they say will further tighten the Egyptian president's grip on power. More than 100 lawmakers from Egypt's largest Islamist opposition group, the Muslim Brotherhood, and other parties refused to attend the session of the 454-seat Parliament because they say the amendments limit judicial monitoring of elections and ban the creation of political parties based on religion - a measure specifically aimed at the Islamic party. The rights group Amnesty International said the proposed reforms, particularly anti-terrorism statutes they contain, will lead to the "greatest erosion of rights in 26 years." The proposal 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," Amnesty International said in a statement Saturday. In December, President Hosni Mubarak asked the legislature to amend 34 articles in the constitution as part of a political reform package - the first major change in the constitution since 1971. But the opposition, which represents about 25 percent of the parliamentary seats, says the changes are cosmetic and will pave the way for Mubarak's son, Gamal, to succeed him in the next presidential elections. The legislature, dominated by Mubarak's governing party, was expected to pass the constitutional amendments later this week. The amendments will then be put to a referendum, which opposition parties are urging Egyptians to boycott. Various activist groups staged small protests in downtown Cairo on Thursday against the reform amid massive police presence. About 30 demonstrators were arrested. Some were released later Thursday and a last batch on Saturday, police and activists said. The Brotherhood is Egypt's strongest Islamic opposition movement. Its 88 lawmakers sit in Parliament as independents because the movement has been banned since 1954. It has been tolerated within strict limits and suffers regular police crackdowns. About 350 Brotherhood activists are currently jailed, according to the movement and the rights group Human Rights Watch.