Pro-Russia supporters take part in a hand vote during a rally outside the regional police building in the eastern Ukrainian city of Horlivka (Gorlovka), near Donetsk
The European Union said Thursday a decision by pro-Moscow rebels to go ahead with an independence vote in east Ukraine would only worsen the crisis.
"Such a vote could have no democratic legitimacy and would only further worsen the situation," a spokeswoman for EU foreign policy Catherine Ashton said.
"Any such type of referendum is not something that we can support," said Maja Kocijancic. "We believe that such referendums should not take place and we fully support Ukraine's territorial integrity and sovereignty and independence."
Rebel leaders in the self-styled Donetsk People's Republic as well as the towns of Slavyansk and Lugansk said they would push ahead with the referendums on Sunday despite a call by Russian President Vladimir Putin to delay them.
"We take good note of President Putin's remarks," Kocijancic said, describing them as "a step that could help de-escalation" but adding that the EU "will see whether words are followed by deeds".
EU foreign ministers gather in Brussels on Monday, a day after the referendums, and could decide to impose more sanctions on Russians and Ukrainians held to be involved in fostering instability in the area.
Ambassadors from the 28 EU nations on Wednesday agreed in principle to expand the legal criteria for targeting people or entities over the crisis.
EU diplomatic sources said one area of concern was Crimea where in recent days there had been reports of companies being taken over following the region's annexation by Russia.
"We do think this is expropriation, confiscation, so we think there is some merit in sanctions" being cast wider, one source said.
An asset freeze, the most likely measure to be imposed on a company, would certainly have some deterrent effect on others, the source added.
The sanctions remit could also be extended to cover cases where an individual or entity is judged to have undermined Ukraine's security, or actively worked against peace efforts, the source said.
The EU so far has imposed asset freezes and visa bans against 48 Russians and Ukrainians for violating or threatening Ukraine's territorial integrity. The new criteria widens the potential circle by targeting those responsible for fostering instability or insecurity, diplomats said.
But EU member states are divided on further action with some hardliners ready for so-called "Phase 3" economic and financial sanctions while others balk at any such idea, insisting there remains much room for diplomacy.
The hawks include the three Baltic nations and Poland, Sweden and the Czech Republic, with backing at times from Britain, while Italy, Cyprus, Hungary, Slovakia, Bulgaria and Greece are at the other end of the spectrum.
"There are very big differences," said an EU diplomat close to the matter.