* Claim Belarus supplied helicopters yet to be verified
* Gbagbo forces frequently attack U.N. staff
ABIDJAN, March 1 (Reuters) - U.N. investigators trying to confirm if Ivory Coast incumbent leader Laurent Gbagbo broke an arms embargo by importing helicopters had to abandon the search at the weekend after his forces shot at them, a spokesman said on Tuesday.
The United Nations has accused Belarus of breaking an arms embargo against Ivory Coast by delivering attack helicopters to Gbagbo, but Gbagbo's government and Belarus denied it on Monday, and U.N. envoys admitted the evidence was not conclusive.
The report came after a week of gun battles between forces loyal to Gbagbo and his rival Alassane Ouattara, almost universally recognised as winner of a Nov. 28 poll, that risk pushing the top cocoa grower back to full-blown civil war.
The accusation was based on reports received by U.N.-appointed experts monitoring the embargo. When they tried to search an airport in the capital Yamoussourko, where they believed the helicopters to be, they were shot at by Ivorian forces, Hamadoun Toure, spokesman for the U.N. mission said.
"That's what they said," he said by telephone, though he did not have any further details and said the investigation about the helicopters was ongoing.
"We are trying to have several details but so far nothing."
Ivory Coast has been under an arms embargo since the last bout of serious violence in 2004, when pro-Gbagbo forces bombed French peacekeepers in the rebel-held north, but analysts say both sides have repeatedly violated it.
Relations between Gbagbo and the U.N. mission, with whom Gbagbo is furious for recognising his rival's win, are deteriorating, with state TV regularly broadcasting stories about their collaboration with rebels.
His often-violent youth supporters responded to a call from their leader Ble Goude at the weekend to block U.N. traffic. Two U.N. staff were kidnapped by a mob on Monday, then released.
Toure said a third was robbed of his wallet. (Reporting by Tim Cocks; Editing by Louise Ireland)
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