Zimbabwean opposition sources say police have detained hundreds of activists in Harare, the capital, ahead of planned protests against the disputed election victory of President Robert Mugabe earlier this month.

Officials of a pro-democracy umbrella group - the National Constitutional Assembly - say more than 350 people, mostly pregnant and breast-feeding women and children were detained Thursday. Those detained were taking part in a workshop ahead of the Saturday protest.

Police have not confirmed the group's allegations.

The protests, set for Saturday, are aimed at lobbying for a new constitution that would curb President Mugabe's widespread powers. The National Constitutional Assembly says Mr. Mugabe used his powers to fraudulently win last month's presidential election.

Zimbabwean police have declared the planned protests illegal under the new Public Order and Security act, but the group has vowed to go ahead, calling the ban unlawful and unconstitutional.

Under Zimbabwean law, penalties for illegal protests range from fines to a year in prison.

Meanwhile, Amnesty International released a report (Friday) saying ruling party militiamen are holding scores of opposition sympathizers and their relatives at illegal detention camps around the country.