WASHINGTON - The United States and the European Union are expected to impose fresh sanctions on Russian individuals on Monday in response to Moscow's alleged efforts to destabilize eastern Ukraine, sources familiar with the matter said.

Obama warns Russia of new sanctions

4 die in renewed Ukraine fighting

The sources, who spoke on condition of anonymity, said the EU was expected to name 15 previously unidentified individuals to be sanctioned and would focus on those whom it believes are responsible for the unrest in Ukraine.

The United States was expected to sanction individuals and entities, they said, with the US list of individuals expected to include "cronies" of Russian President Vladimir Putin.

The sources said the one thing that might prevent the EU and the United States from moving ahead with the sanctions on Monday would be a sudden reversal of what they say is Russian-sponsored separatist movements in eastern Ukraine.

"There will be some overlap, but it won't be huge overlap," said one of the sources familiar with the plans, saying some EU nations remain concerned about sanctioning associates of the Russian leader.

"You will find a European list much more connected to actions on the ground, and an American list more focused on cronies and entities," the source added.

Moscow denies allegations it is directing the separatists, who have taken control of large parts of eastern Ukraine over the past three weeks.

But the White House said US President Barack Obama and European allies agreed on Friday that Russia had escalated tension in the region, where the rebels have declared an independent "People's Republic of Donetsk".