A UN report accuses both the rebel-held north and the government-controlled south of stocking up on weapons, a month before elections.
The report also said neighbouring Burkina Faso is systematically transferring weapons and ammunition to the rebels.
"Despite the arms embargo northern and southern Ivorian parties are rearming or re-equipping with related material," the report by a UN panel of experts said.
"We cannot exclude a situation in which armed violence may escalate rapidly, particularly in the north," the report added.
The UN Security Council is due to renew its arms ban against the country this week, but the report raised the possibility of renewed serious conflict if the political situation deteriorates.
According to the BBC, the authors of the report urged Burkina Faso to investigate the transfer of weapons to rebels in the north.
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