John Makumbe, a political scientist at the University of Zimbabwe and head of the local branch of Transparency International, has been arrested just weeks after warning that civil society was to become the next target of government repression.
Professor Makumbe was one of about 100 trade union and civil society activists arrested last week when police broke up peaceful protests against rights abuses and economic collapse.
The academics included Brian Raftopoulos, chair of the Crisis in Zimbabwe Coalition and an associate professor at the university's Institute of Development Studies, and Lovemore Madhuku, a law lecturer and head of the National Constitutional Assembly, a civil society group for constitutional reform.
They were held in police cells for two days and charged with organising an illegal protest. The charges were later dropped.
Professor Raftopoulos said the Public Order and Security Act had "become a means of abusing activists, seizing them off the streets and holding them for 48 hours as a form of intimidation".
Zimbabwe's government no longer allows protests by groups that oppose its policies. Parliament has been drafting laws requiring non-governmental organisations to register with the government, which will have the power to suspend their leadership.
Professor Raftopoulos said: "We will coordinate a civil society response to the legislation. We will continue to build up pressure on government and to grow and consolidate civil society so we can fight back against rights abuses and reoccupy the political space that government is denying us."