Nigerian authorities have refused to grant permission for the opposition to hold demonstrations against the inauguration of President Olusegun Obasanjo.

The swearing-in ceremony is set for Thursday.

Police have already sealed off a planned protest site in Nigeria's northern city of Kano. It is a stronghold of the main opposition candidate, Muhammdu Buhari.

The coalition of opposition groups have challenged President Obasanjo's landslide victory on April 19. He won his second four-year term during the vote, which was Nigeria's first civilian-organized election in 20 years.

Mr. Buhari charges the vote was rigged and has called on the president to step down and allow fresh elections.

Several international monitors have criticized Nigeria's parliamentary and presidential elections, saying there were serious instances of voter fraud.