Violence has flared once again in the run-up to Senegal's presidential elections, which are due on Sunday.

The latest serious incident occurred on Thursday in the town of Thies, 70km (35 miles) east of the capital Dakar, after President Abdou Diouf made a campaign speech.

Buildings were set alight and several people suffered gunshot wounds.

On Wednesday, at least six people are reported to have been seriously injured and two homes burnt down as opposition and ruling party activists clashed in Rufisque, about 20km (15 miles) east of Dakar.

"This is all a grave sign for democracy in Senegal," said Rufisque's Mayor, Mbaye Jacques Diop.

Closely contested

The elections, which are said to be the most closely contested in the country's history, set President Diouf against the long-standing opposition leader Abdoulaye Wade, and six other candidates.

If no outright winner emerges in the first round of voting, the two leading candidates will contest a second round.

Mr Diouf has been in power since 1981, and his Socialist Party has ruled Senegal since independence from France in 1960.

Mr Wade, leader of the the Senegalese Democratic Party, is standing for the presidency for the fifth time.

On two previous occasions he has accepted portfolios in coalition governments.