The U.N. peacekeeping mission in Ivory Coast says it is concerned that heavy weapons could be used against civilians as rival presidents struggle for power.
In a statement Tuesday, the mission said forces loyal to incumbent president Laurent Gbagbo are repairing an attack helicopter and preparing multiple rocket launchers for use.
The mission called the weapons "a grave threat to the civilian population" and warned Gbagbo forces that the U.N. would act if such weapons are used.
Earlier, Ivory Coast's internationally recognized president, Alassane Ouattara, called on the United Nations to authorize "legitimate force" to protect civilians.
Mr. Gbagbo has resisted calls to relinquish power to Mr. Ouattara, who the United Nations and African Union back as the winner of a November president poll.
Since the election, supporters of the rival presidents have engaged in intense fighting, sparking fears that Ivory Coast may be on the brink of a civil war.
The U.N. says more than 435 people have been killed in post-election violence.
Aid groups say about 90,000 people have fled to neighboring Liberia and some 300,000 have been displaced in the main commercial city of Abidjan.
Some information for this report was provided by AP, AFP and Reuters.