Ivory Coast leader Laurent Gbagbo has been captured at his residence in the city of Abidjan.
The defence ministry in France says he was arrested on Monday by the forces of his opponent, Alassane Ouattara, with French and United Nations military support.
Mr Gbagbo refused to step down as president after an election last November.
He was taken to the headquarters of Mr Ouattara, who the UN says won the election.
Mr Gbagbo's wife was also arrested.
Ivory Coast's permanent representative to the United Nations says Mr Gbagbo will be put on trial.
Youssoufou Bamba also said Mr Gbagbo's forces should now lay down their arms and end the fighting.
Forces loyal to Mr Ouattara launched an offensive from their stronghold in the north at the end of March, after months of political deadlock.
On Sunday, UN and French helicopters launched a new wave of air strikes after the hotel used by Mr Ouattara came under fire on Saturday.
The BBC reports French tanks were seen advancing on the official residence on Monday.
The UN announced that Mr Gbagbo had surrendered to Mr Ouattara's forces.
France said pro-Ouattara troops had detained him, but aides to Mr Gbagbo said it was French special forces.
US Secretary of State Hillary Clinton says Mr Gbagbo's arrest should serve as a message to other dictators.
Meanwhile, Mr Ouattara has urged restraint. In a televised address, he appealed to Ivorians to abstain from all reprisals and violence.
He has promised Mr Gbagbo a fair trial and said a truth and reconciliation commission will be set up.