The BBC’s John James in Abidjan says the situation remains unstable
The African Union says it is sending former South African President Thabo Mbeki to Ivory Coast to help mediate the current political crisis.
Laurent Gbagbo and opposition candidate Alassane Ouattara have both sworn themselves in after claiming victory in a presidential run-off.
Mr Ouattara was initially declared the winner but the results was overturned in the incumbent’s favour.
The AU has warned the crisis could have “incalculable consequences”.
In a statement, the organisation rejected “any attempt to create a fait accompli to undermine the electoral process and the will of the people”.
It called on all parties to “show the necessary restraint and to refrain from taking actions which will exacerbate an already fragile situation”.
Several countries and international organisations – including the US, UN, France and the IMF – have backed Mr Ouattara as the true winner of last Sunday’s run-off.
The AU has not said when Mr Mbeki is likely to travel to Ivory Coast, but the BBC’s John James in the capital Abidjan says his arrival is being widely discussed.
The crisis has already led to unrest on the streets of the capital When he was president of South Africa, Mr Mbeki helped to mediate a peace deal in Ivory Coast.
But he was seen by the opposition as being uncomfortably close to Mr Gbagbo.
It is difficult to see what scope there is for Mr Mbeki to mediate, says our correspondent, as both men are adamant that they legitimately won the poll.
The fear is that if he fails to find a way out, rebel groups in the north who support Mr Ouattara will take up arms in protest.
Mr Ouattara was declared the winner by the Election Commission on Thursday, but on Friday, its ruling was overturned by the Constitutional Council, which is led by an ally of the incumbent, Mr Gbagbo.
“it’s just a brief episode – I want to tell you that Ivory Coast is now in good hands”
Alassane Ouattara
Mr Gbagbo, who has the backing of the head of the country’s armed forces, was sworn in for a third term in office at the presidential palace on Friday afternoon.
He repeated the accusations of fraud that had led the Council to discount large number of ballots in the north, where Mr Ouattara’s supports is strongest.
“You think that you can cheat, stuff ballot boxes and intimidate voters and that the other side won’t see what is going on,” Mr Gbagbo said.
He also said he had noted “serious cases of interference” in recent days, referring to international disapproval of his return to power.
“We didn’t ask anyone to come and run our country. Our sovereignty is something I am going to defend,” he said.
But within hours, Mr Ouattara, a former rebel from the predominantly Muslim north of the country, was himself sworn in, at an Abidjan hotel guarded by UN peacekeepers.
He said the election had been “historic” and that he was proud of it, but that the last few days had been “difficult”.
“But it’s just a brief episode – I want to tell you that Ivory Coast is now in good hands,” he said.
Mr Ouattara immediately re-appointed Guillaume Soro as his prime minister. Mr Soro had tendered his resignation in Mr Gbagbo’s administration just hours earlier.
Mr Soro – who is the head of the New Forces rebels in the north – has warned that overturning the results threatens to derail attempts to stabilise and reunify the country after the 2002 war.
The political crisis has led to protests on the streets of the country’s main city of Abidjan, with opposition supporters saying Mr Gbagbo’s investiture amounts to a coup d’etat.
At least four people have been killed in election-related clashes in Abidjan this week.
Ivory Coast has closed its borders and stopped broadcasts of international news media into the country. An overnight curfew remains in place over the weekend.
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