MOSCOW (AFP) - Russia said on Friday it reserved the right to protect its compatriots in the whole of Ukraine, after a protester was killed in fresh clashes in the east of the country.

The statement appears to dramatically raise the stakes in the Ukrainian crisis, and will be seen as Russia hinting it may move its forces beyond the Russian-speaking peninsula of Crimea.

"Russia recognises its responsibility for the life of its compatriots and fellow citizens in Ukraine and reserves the right to protect people," the Russian Foreign Ministry said in a statement.

A pro-Kiev protester was stabbed and killed on Thursday and several were injured in clashes in the Russian-speaking Ukrainian city of Donetsk, the first death since tensions erupted in the south-east of the country after pro-Russian forces took control of Crimea.

"We have repeatedly stated that those who have come to power in Kiev should disarm militants, ensure the safety of the population and people's legal right to hold rallies," the Foreign Ministry said.

"Unfortunately, as the events in Ukraine demonstrate, this is not happening, (and) the Kiev authorities do not have the situation under control."

Historic and linguistic faultlines divide the former Soviet nation of 46 million into the Russian-speaking, Moscow-leaning east and the Ukrainian-speaking pro-Western west.

Russia stunned the West by sending troops to the Crimean Peninsula after a popular uprising in Kiev ousted President Viktor Yanukovych last month.