Violence has erupted in Senegal after the country's top court ordered that President Abdoulaye Wade can run for a third term in office in February elections.
Protesters set buildings on barricades on fire in the capital, Dakar.
Officials said one policeman had been killed in the unrest.
The BBC says Dakar is under tight security following the clashes between opposition supporters and government troops.
The Constitutional Council on Friday validated the candidacy of Mr Wade, 85, and 13 others, but rejected the presidential candidacy of Senegal's best-known music star Youssou N'Dour, saying the signatures he had gathered to support his candidacy could not be verified.
The Grammy Award winner said the decision amounted to a coup d'etat.
"The constitutional coup d'etat has been completed," he said. "Fifty-two years of democratic constitution has just been swept away..... We have been betrayed by this shameful decision."
Opposition leaders have said they are ready to fight to ensure Mr Wade does not run in elections, to be held on 26 February, arguing that the constitution limits the number of terms a president can serve to two. He has been in power since 2000.
For his part, Mr Wade argues that when the new constitution was brought in in 2001 it was not retrospective and so his first term as president should be considered the one that started after the changes - namely in 2007.
All the judges, who were appointed by the President, agreed with that position.