Cairo, Egypt - The authorities in Egypt have detained almost 500 Muslim Brotherhood members, whose group is illegal but normally tolerated, since the start of May, the Egyptian Human Rights Organisation said.
It said it had a list of 498 members "detained during peaceful demonstrations organised over the month of May in several governorates" of Egypt.
"The police resorted to violence by striking out at demonstrators with batons and using firearms and tear-gas grenades," it said in a report, a copy which was received by AFP.
It quoted witnesses as saying police fired rubber bullets at protesters.
Tariq Mahdi Ghanam, a 40-year-old school teacher, died on May 6 after police used tear gas and rubber bullets to disperse a pro-reform rally in the Nile Delta city of Mansura, according to the Muslim Brotherhood.
The Brotherhood members were detained amid a wave of demonstrations calling for political reform in Egypt.
Under growing domestic and international pressure, 77-year-old President Hosni Mubarak agreed in February to amend the constitution to allow competitive presidential elections for the first time.
The Brotherhood has 17 MPs in parliament but the continuing ban on its activities means that all were elected as independents. It has rejected Mubarak's amendment as cosmetic.
The amendment, approved by parliament on May 10, sets a raft of conditions for candidates to be registered that the opposition says effectively excludes everyone except members of Mubarak's ruling party.
Egyptians are to vote on the constitutional amendment in a May 25 referendum.