UN Secretary-General Ban Ki-moon says Belarus may be sending three attack helicopters to military forces supporting Ivory Coast's longtime ruler, Laurent Gbagbo, in violation of an international arms embargo.
Ban has called for an urgent meeting of the UN Security Council to discuss the matter.
Gbagbo has refused to cede power since Ivory Coast's election commission declared challenger Alassane Ouattara the winner of November's election, and armed fighting between the two sides has raised fears of a new civil war in the African country.
A statement from Ban's office said the reported Belarusian arms shipment was "a serious violation" of the embargo against Ivory Coast in place since 2004. He said the UN had "credible information" to substantiate the report.
A first delivery of helicopters reportedly arrived late on February 27, with additional flights expected on February 28.
The French news agency AFP, citing an unnamed UN source, reported that forces loyal to Gbagbo opened fire on February 28 on UN sanctions experts who had gone to an airport in the capital, Yamoussoukro, to investigate reports of the embargo breach.
The Belarusian authorities have firmly denied the accusations.
"We are concerned by this statement. The Republic of Belarus has always had a very responsible attitude toward respecting all the decisions of the UN Security Council," Belarusian Foreign Ministry spokesman Andrey Savinykh told RFE/RL. "We declare that no attack helicopters were delivered to the Ivory Coast from Belarus."
Savinykh added that Minsk has doubts about the UN statement's authenticity.
"There is a need to find out where this material comes from and how it appeared on the UN's official website," he said. "It may have no connection at all with the UN secretary-general's office."
RFE/RL's correspondent at the UN spoke to a representative of the Belarusian delegation, who also denied the reports.
Fears Of Escalation
The scandal comes a week after renewed street battles in Ivory Coast left several dozen people dead.
The UN refugee agency says that fighting at the weekend in Abidjan had pushed some 30,000 civilians to flee the city.
The helicopter shipment would give Gbagbo air power after the country's air force was destroyed by the French military during the country's earlier civil war, which began in 2002.
This could pose a danger for Ouattara, who has taken refuge inside Abidjan's Golf Hotel together with hundreds of his supporters.
Belarus itself drew international condemnation in December when its authoritarian president, Alyaksandr Lukashenka, won a fourth term in an election widely regarded as fraudulent.
Meanwhile, a Swedish think tank specializing in arms trade research says that it suspects Libya also recently received a shipment of military equipment from Minsk.
The Stockholm International Peace Research Institute says that an Ilyushin-76 aircraft left a military base near the Belarusian city of Baranovichi and landed at the Libyan airport in Sebha in mid-February.
Libyan leader Muammar Qaddafi is currently arming a counteroffensive against antigovernment forces who have seized large swathes of the country in the past two weeks.
written by Claire Bigg, with reporting from RFE/RL's Belarus Service and news agencies