Russian President Vladimir Putin is "talking through his hat" by calling for separatists in east Ukraine to delay an independence vote, Ukrainian Prime Minister Arseniy Yatsenyuk said late Wednesday.

"Vladimir Vladimirovich (Putin) is talking through his hat," Yatsenyuk said, according to the Interfax-Ukraine news agency.

"It would be much better for the Russian president to be informed that no referendum was scheduled to take place in Ukraine on May 11," he said, dismissing the rebel vote plan as unofficial because it was not organised by his government in line with the constitution.