Zimbabwean riot police in the capital Harare fired tear gas and used water cannon on Wednesday to break an opposition protest calling for fair elections next year.
The Movement for Democratic Change (MDC) party had planned a march against voter registration centres which it says favour long-ruling President Robert Mugabe.
A heavy police presence was on duty from early morning, and officers moved in to prevent marchers from gathering in the city centre.
An AFP correspondent witnessed shopkeepers pulling down shutters and locking doors as tear gas cannisters were fired from passing police trucks.
On the street, police wielding batons dispersed protesters and bystanders trying to escape the stinging fumes.
“Heavily armed police officers brutally crushed our peaceful demonstration,” MDC youth secretary general Lovemore Chinoputsa said in statement.
Mugabe, who has been in power since independence in 1980, is the ZANU-PF candidate for the election despite being 93 and in poor health.
He is currently in Singapore for a medical check-up.
His party is riven by rivalry over his succession, while opposition parties are in talks to unite behind one candidate.
Last year a series of large anti-Mugabe protests that shook the government were ended in a security crackdown.