Amnesty International is calling on the Egyptian authorities to release or charge all detained supporters of opposition groups ahead of next month's parliamentary elections, following a new wave of arrests.

At least 75 members of the Muslim Brotherhood were arrested on Tuesday in police raids on homes in Alexandria, where they were involved in election campaigning, and Amnesty International has learnt that about 10 more were arrested subsequently.

All have been detained without charge.

Four members of an opposition youth activist group, the 6 April Movement, were also arrested. They were charged with holding an unauthorised public gathering and distributing leaflets calling for a boycott of the election. They were subsequently released on bail.

Malcolm Smart, Amnesty International's director for the Middle East and North Africa, said:

"These arrests are the latest evidence of a growing government clampdown on the Muslim Brotherhood and other opposition groups in the run up to the first round of the elections on 28 November.

"The Egyptian authorities must respect the rights of opposition groups and activists to undertake peaceful campaigning without interference or persecution, if the elections are to be free and fair. All those detained must be released unless they are charged with a recognisable criminal offence."

More than 260 supporters of the Muslim Brotherhood have been arrested since its chairman, Mohamed Badie, announced on 9 October that the group will put up candidates for election.

Most, including more than 70 who were arrested earlier this month, have since been released.

The four members of the 6 April Movement - an online network started on Facebook in 2008 to support on-strike workers in the town of El-Mahalla El-Kubra - have been named as Salwan Muhammad Said, Mohammad Abdallah, Mahmoud Ahmed Hamed and Magdy Abdel-Rahman.

The Muslim Brotherhood has been officially banned in Egypt since 1954. However, it has continued to operate openly and leaders and supporters of the organisation have stood as independent candidates in previous parliamentary elections, in many cases successfully.

It has wide popular support and is generally seen as the main rival to Egypt's ruling National Democratic Party.