CAIRO, Egypt (AP) -- Police arrested 75 members of the Muslim Brotherhood on Thursday in what appeared to be a pre-emptive strike against Egypt's strongest opposition group ahead of parliamentary elections and a key debate.

A Brotherhood official said the detentions risked provoking violence — not from the group itself, but from those who would infer the state was leaving no room for peaceful Islamic political activity.

The arrests bring the total of Brotherhood members in custody to just under 300, according to figures provided by the group and the New York-based Human Rights Watch. The Bush administration has recently eased its public calls for reform by President Hosni Mubarak, a key U.S. ally in the Middle East.

The Muslim Brotherhood, Egypt's largest Islamic political group, has been banned since 1954. It is tolerated, within strict limits, but suffers regular police crackdowns.

Police did not give a reason for the early morning detentions, but those arrested were mostly Brotherhood members expected to stand in the April elections for the Shura Council, the upper house of parliament, said Abdel Gelil el-Sharnoubi, the editor of the Brotherhood's Web site. "They also arrested a number of legislators' assistants in order to paralyze the lawmakers," he said. El-Sharnoubi said the group had not yet chosen its candidates for the Shura polls, but that the authorities targeted "figures who are popular in their provinces and are expected to run the elections."

The Brotherhood did surprisingly well in the 2005 legislative elections, winning 88 seats in the 454-member parliament. The government then postponed 2006 municipal elections for two years, apparently out of fear of more Brotherhood gains.

Brotherhood candidates run as independents, but their campaigns are financed by the group and voters know their allegiance.

Abdel Moneim Aboul Fotouh, a Brotherhood leader, acknowledged that the crackdown would impede the group's ability to campaign.

"There is no doubt about that. Those who have been arrested are national, reputable people," he said on Al-Arabiyah television. The mass detention was irresponsible, he added, warning it was an "indirect call by the regime for violent forces to become active because it is crushing all the peaceful factions."

Mubarak recently asked the legislature to amend 34 articles in the constitution as part of a political reform package.

The opposition has criticized the amendments as doing little to advance democracy. One amendment would ban the formation of political parties with a religious foundation — a restriction clearly aimed at the Brotherhood.

The vote on the amendments is also due in April but a precise date has not been set.

The authorities have intensified their campaign against the Brotherhood since December, when student members staged a militia-style demonstration at Al-Azhar University in Cairo. The parade, which Brotherhood leaders said was unauthorized, provoked fears that the group was forming a military wing.

Mubarak signed an order last week to put 40 Brotherhood members on trial in a military court on charges of money laundering and terrorism. The accused include the group's No. 3 leader, Khayrat el-Shater, official Mohammed Ali Bishr, and a millionaire businessman patron of the group, Hassan Malik.

Human Rights Watch said Thursday — before the latest arrests were made public — that the police had detained a total of 226 group members "solely for exercising their rights to freedom of expression and association" since December.

Sarah Leah Whitson, the Middle East director of Human Rights Watch, accused the government of trying to crush the Brotherhood. "The government has shown once again that it cannot tolerate any criticism," she said.