By Mark Doyle
BBC News, Kinshasa
Riot police in the Democratic Republic of Congo have broken up a large protest march in the capital, Kinshasa, by one of the main opposition parties.
The party claims the electoral system is unfair
The Union for Democracy and Progress (UDPS) opposes the electoral system, saying it is stacked against them.
The rally was held on the main airport road, following rumours that President Joseph Kabila was returning to the city by air after a tour of the country.
The country is preparing for its first free presidential elections.
The protest turned into a dangerous game of cat and mouse between thousands of opposition supporters and hundreds of anti-riot police.
The protestors threw stones and the police fired warning shots in the air.
The opposition UDPS party says the elections are unfair because they do not have representation on key committees which are running next weekend's polls.
For this reason they will boycott the exercise.
The UDPS has historically been a major force in Congolese politics.
During the time of the long-running single party dictatorship of President Mobutu Sesi Seko, the UDPS was the most prominent group calling for a multi-party system.
In more recent years however the war, which ended in 2003 with a peace agreement, has sidelined the party as a potent force.
Some people also believe the UDPS leader, Etienne Tshisekedi, made a political miscalculation last year when he boycotted a referendum which paved the way for this week's elections.
His loyal supporters say he has been sidelined because he is an anti-establishment figure.
Whichever is correct, the protest on the airport road and its muscular break-up by the police add to the tense atmosphere in the run-up to this weekend's polls.