"Any attack against peacekeepers constitutes a crime under international law, for which the perpetrators and those who instigate them will be held accountable," Ban said.

Expressing his concern about "the deteriorating situation in Cote d'Ivoire," Ban said he was "deeply alarmed" to learn of the call by supporters of Gbagbo to attack the UN-protected Golf Hotel in Abidjan, where Ouattara has his headquarters.

"Any attack on the Golf Hotel could provoke widespread violence that could reignite civil war" and Ban called on people "contemplating participation in the attack to refrain from such dangerous irresponsible action."

He urged Ivorians to "contribute instead to the restoration of lasting stability and democracy in their country."

Tensions have been mounting in the West African nation for more than a month after the disputed presidential election.

World leaders have urged self-declared President Laurent Gbagbo to cede power in favor of Alassane Ouattara, who is considered the rightful winner of last month's poll.