MOSCOW (AFP) - The Russian Black Sea fleet based in Crimea denied on Monday there were plans to storm Ukrainian military positions on the peninsula, calling reports of an ultimatum "nonsense," Interfax said.

"That is complete nonsense," a representative of the fleet was quoted as saying after Ukraine's regional military said it had received an ultimatum to surrender early Tuesday or face attack.

"We are used to daily accusations about using force against our Ukrainian colleagues," he said. "Efforts to make us clash won't work."