Liberian President Charles Taylor has been indicted for war crimes by a United Nations-backed court in Sierra Leone.
Taylor: Former warlord turned president is facing a rebellion
Mr Taylor is currently in neighbouring Ghana, where he opened peace talks with rebels by offering to stand down.
A warrant for his arrest has been served on the Ghanaian authorities and sent to Interpol, said the court's chief prosecutor, David Crane.
Mr Taylor is accused of being the principal backer of Sierra Leone rebels during a brutal 10-year civil war which ended in 2002.
The Special Court for Sierra Leone accuses Mr Taylor of crimes against humanity and violations of international humanitarian law.
However, Ghana's interior and foreign ministers have both told the BBC that they have not officially been asked to arrest Mr Taylor.
The BBC's Paul Welsh at the peace talks in Accra says the Ghanaians appear not to have the will to arrest him.
1989: Launches rebellion
1991: RUF rebellion starts in Sierra Leone
1995: Peace deal signed
1997: Elected president
1999: Lurd starts rebellion to oust Taylor
Diplomats suggest that the need for peace talks on Liberia has been judged more important than the need for Charles Taylor to stand trial.
Our correspondent says that Mr Taylor strode confidently onto the platform to take his place next to South African President Thabo Mbeki.
Mr Taylor said that he was ready to form a national unity government immediately, without necessarily taking part.
"If President Taylor removes himself for the Liberians, will that bring peace? If so, I will remove myself," he said.
Several African leaders attended the opening ceremony but neither of the two rebel groups participated.
Mr Taylor is already the subject of UN sanctions for his alleged role in the civil war, in which tens of thousands of people were killed.
Many more had their limbs hacked off with machetes.
Thousands were mutilated during the Sierra Leone civil war
Mr Crane said that Mr Taylor had been indicted on 7 March and passed to the Ghanaian authorities when he had left Liberia.
He denied that the indictment could disrupt the peace talks in Ghana.
"The timing of this announcement was carefully considered in the light of the important peace process begun this week... It is imperative that the attendees know they are dealing with an indicted war criminal," he said.
The BBC's World Affairs correspondent, Mark Doyle, says that under President Taylor the country has become something of a pariah state.
The UN renewed the sanctions last month, widening them to include the logging industry - the largest source of government revenue.
The head of the UN refugee agency, Ruud Lubbers, has called for the president's removal from office.
Mr Taylor, in turn, says the Liberian rebels are former warlords who have also committed gross human rights violations.
Western and African diplomats say Mr Taylor had agreed to take part in the peace talks in Ghana because of the huge gains made by the rebels in recent months.
Now Lurd rebels hold more territory than the government and can even launch attacks on Monrovia.
Hundreds of thousands have been displaced in Liberia
The head of the former Sierra Leone Revolutionary United Front rebels, Foday Sankoh, is among the nine people previously indicted by the Special Court.
Seven of these are in custody.
Last month, the court urged Mr Taylor of harbouring one of Mr Sankoh's deputies, Sam Bockarie.
Shortly afterwards, the Liberian authorities said he had been killed in a shoot-out with their forces.