UN Secretary General Kofi Annan has confirmed that presidential elections in Ivory Coast would not take place on 30 October as originally planned.
The country has been divided between north and south since 2002
He told Radio France International (RFI) a lack of co-operation had delayed preparations.
Both the rebels and opposition parties have rejected the poll, saying it could not be free and fair at that time.
Ivory Coast has been divided between north and south for three years, with armed rebels controlling the north.
Some 6,000 French troops are in the west African country along with 4,000 UN troops, monitoring a buffer zone between rebel forces and the army.
"[The election] is not going to be possible because the political leaders and parties have not co-operated," Mr Annan told RFI, adding that the UN had not even been able to set up an electoral commission.
"I think that sooner or later the (UN Security) Council will be obliged to act," he added.
The election was part of a peace deal brokered by South Africa to end the rift between the rebel-controlled north and the government-held south.
There are a number of unresolved issues, with New Forces rebels refusing to co-operate with South African mediators.
They are also unhappy with legal reforms on identification, nationality and electoral laws.
Numerous militias who support President Laurent Gbagbo are still to be dismantled.
The rebels and the opposition want a transition government without Mr Gbagbo to be formed, before elections can be held.