The European Union said it would not recognize the result of a referendum on self-rule held by pro-Moscow rebels in east Ukraine, calling it illegal.
"The so-called referenda in ... parts of the Luhansk and Donetsk regions were illegal and we do not recognize the outcome. Those who organized the referenda have no democratic legitimacy," said Maja Kocijancic, a spokeswoman for EU foreign policy chief Catherine Ashton.
She said Sunday that holding the referendum ran counter to the objectives of an agreement reached by Ukraine, Russia, the EU and the U.S. last month that aimed to defuse the Ukraine crisis.
Nearly 90 percent of voters in Donetsk, the larger of two eastern Ukrainian regions where a referendum was held, voted for self-rule, the head of the separatist election commission there said.
Ukraine's Crimea region was annexed by Russia in March after a similar vote.
Kocijancic said the EU encouraged the Ukraine government to push ahead with efforts to reach out to all regions through a proposed national dialogue, including steps towards an inclusive dialogue on constitutional reform.
Ukraine's government said last week it was ready to talk to political parties and regional officials in eastern regions on ways to resolve the country's crisis, but would not talk to "terrorists."
The EU urged all parties to support holding free and fair presidential elections on May 25, Kocijancic said.
The upheaval in Ukraine broke out after former pro-Russian President Viktor Yanukovich turned his back last year on a trade and political cooperation deal with the EU in favor of a $15 billion bailout from Russia, sparking prolonged street protests that ended with him fleeing Ukraine.