Thousands of Kenyan police deployed across Nairobi on Friday to block a fresh attempt by supporters of defeated presidential opposition candidate Raila Odinga to hold a rally in the capital.
Police used tear gas and water cannon on Thursday to prevent thousands from gathering in the city centre, resulting in running battles on the edges of the city.
Riot police and paramilitary units once again patrolled the main access points on Friday and fanned out around Uhuru (independence) Park, where the demonstration was planned.
Others gathered near volatile slum areas from where thousands of Odinga's Orange Democratic Movement (ODM) supporters were expected to begin marching to protest President Mwai Kibaki's re-election last week, AFP correspondents and officials said.
"We once again warn that we will not allow anybody to hold a rally in the city. Such meetings have been banned," police spokesman Eric Kiraithe told AFP.
Officials warned that opposition rallies could lead to violence, after post-election riots and tribal clashes killed more than 350 people.
"We have information that the ODM leaders want to call for a march to State House, which could prove very fatal. That is why these people should forget meeting in Nairobi," a police commander told AFP.
Pre-poll frontrunner Odinga claims the government rigged the vote count to re-elect Kibaki and has called for one million people to attend the Nairobi rally where his party intends to declare him "the people's president".
Sunday's announcement by the electoral commission that Kibaki had won the disputed election touched off Kenya's worst urban clashes in 25 years and displaced tens of thousands of people.