Pro-Russian separatists in eastern Ukraine are calling this weekend's referendum a victory.
Organizers say about 90 percent of those who voted in the Donetsk and Luhansk regions voted for sovereignty. But with no international election monitors in place, it was not possible to verify the claims.
Separatists say the ultimate status of the regions could include secession or annexation by Russia.
Both the Ukrainian government and the West have rejected the referendums as illegal.
Russia is making it clear that it has no intention of immediately annexing the two eastern Ukrainian regions, unlike their hasty incursion after the referendum in Crimea.
Meanwhile, European Union foreign ministers added 13 people Monday to their visa ban and asset freeze list over Ukraine's crisis. But the ministers are not expected to decide whether to impose broader economic measures on Russia before Ukraine's May 25 elections.
The 28 EU ministers also said in a statement that two firms in Russia-annexed Crimea would be hit with asset freezes later Monday.