Russia's unprecedented step - the withdrawal of the Russian ambassador from Ukraine - means that Russia is extremely concerned about the situation in that country, aid Russian Prime Minister Dmitry Medvedev.

"Our ambassador has been recalled for consultations. I think you understand without my explanations what this means in diplomatic practice," Medvedev's said in Sochi in answer to a question from Interfax.

Such a step means, said Medvedev, that "it is not clear to us what is going on there, and that there is a real threat to our interests, and to our citizens' lives and health," he said.