Police raided a meeting of opposition and reform groups at a church on Thursday, arresting a bishop and four human rights activists, witnesses said.
Mike Davies, a member of the Crisis in Zimbabwe Coalition, said police used riot sticks to disperse the 60 or so people who gathered to discuss the role of the churches in Zimbabwe's deepening political and economic crisis. The coalition is an alliance of reform groups.
Bishop Trevor Manhanga, who is head of the multidenominational Ecumenical Fellowship of Zimbabwe, was among those arrested by police. Witnesses said police were provoked when Manhanga asked to pray for them as they broke up the meeting.
Also arrested at the Northside Community Church were human rights lawyer Brian Kagoro, university political scientist John Makumbe, activist John Stewart and a church worker, he said.
An official of the US Agency for International Development was also arrested but released when her identity was made known to police, Davies said.
Burnt a flag
It was unknown what those arrested would be charged with.
Davies said police had been informed in advance of the meeting as required under the nation's sweeping security laws. Officers told those attending the meeting that it had not been approved.
Police officials were not immediately available for comment.
Earlier on Thursday, demonstrators burnt a flag of Nigeria at the west African nation's diplomatic offices in Harare to protest that country's support for Zimbabwe President Robert Mugabe.
On Wednesday, the European Union renewed diplomatic sanctions against Mugabe's government, accusing it of violating human rights and pursuing policies that have led Zimbabwe into economic and political chaos.
Mugabe has cracked down on the independent press, the judiciary, opposition officials and human rights workers in recent years.